Who makes money if hormone monitoring moves from occasional tests to daily care?

Hormone monitoring is not a single market. It sits at the intersection of laboratory chemistry, fertility medicine, home testing, wearable computing, telehealth and hormone drugs—businesses with different histories and revenue models. Today, the dependable business remains mostly occasional: laboratories sell validated results; fertility clinics use repeated measurements to time costly treatment; and drug makers and care providers sell medicines and access. Daily care has drawn attention as menopause treatment grows, venture capital backs hormone sensors, and consumers become accustomed to tracking other aspects of their health. But it expands the profit pool only when more frequent data change a real decision. Until then, the likely winners are owners of validated assays, collection networks, clinical workflows and recurring consumables—not necessarily the makers of the most appealing dashboard.

The measurement that made hormones visible

In 1950, the Bronx Veterans Administration hospital in New York operated a small radioisotope unit, part of a broader effort to put atomic-age materials to medical use. Its physicist was Rosalyn Yalow, who had overcome barriers to enter nuclear physics and joined the VA to explore medical applications for isotopes. That year, she began working with Solomon Berson, a young internist. Their two-decade partnership produced one of the defining laboratory methods of the twentieth century.¹

Their initial question was narrow: why did some diabetic patients treated with animal insulin clear it from their blood more slowly than people who had never received an injection? Using insulin tagged with radioactive iodine, Yalow and Berson showed that these patients had developed antibodies to the foreign insulin. The finding initially met resistance; Yalow later recalled in her Nobel lecture that reviewers rejected the original paper because they did not accept that insulin could provoke antibodies.²

That rejected finding became the key insight. If an antibody binds insulin, the binding can be used to measure insulin.

A contest for a lock

Hormones were already known as chemical messengers released by one organ to instruct another. The problem was scale: many circulate at concentrations too low for the chemistry of the time to detect. Yalow and Berson's radioimmunoassay solved this through competition. A fixed quantity of radioactively tagged hormone is mixed with a fixed amount of antibody, then a patient's blood is added. The patient's hormone competes with the tagged version for the same antibody “locks.” More hormone in the sample means less tagged hormone is bound. Measuring radioactivity against known standards turns an otherwise invisible concentration into a number.

The lock-and-key analogy has limits. Real assays require calibrators, controls and careful handling of similar molecules that may also bind to an antibody. But the principle was broadly applicable. Their work in the late 1950s made plasma insulin measurable, and the same approach could be applied to almost any hormone for which an antibody could be raised.² Yalow received the Nobel Prize in 1977. Berson had died in 1972, and the prize is not awarded posthumously.¹ They did not patent the method, which spread through endocrinology and fertility medicine and, later, into home pregnancy tests.¹

The trouble with look-alike keys

A second scientific thread complicates the first. Steroid hormones such as estradiol, the main circulating estrogen, and testosterone share the same four-ring chemical skeleton and differ only in small details. Antibody-based tests, or immunoassays, are fast, inexpensive and readily automated at high volume. But they can confuse close chemical relatives and perform worst at low concentrations—such as estradiol levels in men, children, postmenopausal women, or women taking drugs that suppress estrogen. The Endocrine Society warned that many routine estradiol assays lacked the sensitivity and specificity these patients require.³

The more selective alternative is liquid chromatography-tandem mass spectrometry, or LC-MS/MS. If an immunoassay resembles trying a key in a lock, LC-MS/MS first separates a bag of similar keys by how quickly they travel through a column, then measures each molecule and its fragments. That makes it better able to distinguish estradiol from related compounds. It is not a universal solution: it requires costly instruments, skilled staff and careful calibration, and results may still differ between laboratories.

That variation is why the US Centers for Disease Control and Prevention (CDC) runs its Hormone Standardization Program, comparing laboratories' and manufacturers' estradiol and testosterone methods with reference measurements.⁴ The CDC described the programme in 2008 as a response to assay variation that had become a clinical problem.⁵

The original bargain

Radioimmunoassay established a business model that still shapes diagnostics. A company places an analyser in a hospital or laboratory, often on favourable terms, then earns recurring revenue from the reagents, calibrators and controls the laboratory uses. This reagent pull-through model is sticky: a hospital that has interpreted years of results within one company's measurement system cannot easily switch. Reference ranges, validation work, information systems and clinician habits would all need to change together.

The companies that own much of this infrastructure are among medicine's largest. Abbott Laboratories $ABT reported $8.9bn in diagnostics revenue in 2025, Roche CHF13.8bn and Siemens Healthineers $SHL.DE €4.3bn; Beckman Coulter sits inside Danaher $DHR, while DiaSorin $DIA.MI is a smaller specialist whose immunoassay menu has long included endocrinology.⁶ Thermo Fisher Scientific $TMO, Waters $WAT and Agilent $A supply the mass-spectrometry and chromatography tools used for selective steroid testing. None discloses the share of revenue generated by hormone tests. For the large platforms, hormones are one test category within a much broader menu.

Further downstream, the laboratories that perform the tests became businesses in their own right. Quest Diagnostics $DGX and Labcorp $LH, the two largest US networks, collect samples, run assays at scale and return results.

Seeing is not knowing

Better instruments do not automatically create a monitoring market. More than half a century after Yalow and Berson, conventional laboratory results for estradiol and testosterone still require a federal programme to compare them with reference methods.⁴ If established laboratories need that discipline, a new consumer sensor begins with a harder problem, not an easier one.

The deeper tension runs through the rest of this story: measurement is not interpretation. Seeing a hormone level more often does not, by itself, demonstrate that treatment or quality of life improves.

As laboratories made hormones legible, drug makers were turning them into medicines that millions of people would take daily—and that clinicians would need to manage.

↑ Back to Top

The pill turns a laboratory subject into everyday medicine

On 9 May 1960, the US Food and Drug Administration approved G. D. Searle's Enovid for contraception.⁷ The drug emerged from an unusual coalition: Gregory Pincus, a biologist studying hormonal control of ovulation, supplied the science; John Rock, a Catholic gynaecologist in Boston, led the clinical work; Margaret Sanger campaigned for a pill for decades; and Katharine McCormick, an heir with a biology degree, largely financed the research. Enovid had been approved in 1957 for menstrual disorders; the 1960 decision added the use that reshaped its social and commercial significance.⁸

The pill expanded hormonal medicine's scale. Millions of healthy women began taking synthetic hormones daily, often for years. It established concepts that still frame the category: cycles, dosage, side effects, long-term risk and the management of reproductive biology.

It did not, however, create routine hormone measurement. Women taking the pill did not receive daily blood tests. Instead, long-duration treatment expanded adverse-event surveillance and prescribing rules: the monitoring focused on patients, not on hormone concentrations.

The older menopause franchise

Menopause therapy is older still. Premarin, a mixture of conjugated estrogens originally extracted from pregnant mares' urine, was approved in the United States in 1942 and is now sold by Pfizer $PFE.⁹ The modern menopause market is therefore a revival of one of pharmacy's longstanding drug franchises.

Terms matter. HRT, or hormone replacement therapy—also called menopausal hormone therapy, or MHT—usually refers to estrogen, often combined with a progestogen, prescribed to relieve symptoms such as hot flushes and night sweats and to protect bone. It differs from contraception, fertility drugs and testosterone therapy, though these treatments use related molecules and may be sold by the same companies.

The companies in this market inherited commercial infrastructure built around the pill and Premarin: sales forces serving gynaecologists and general practitioners, pharmacy and formulary relationships, and regulatory expertise for mature products. Bayer $BAYN.DE has a longstanding women's-health portfolio. Organon $OGN focuses on women's health, fertility and established brands. Viatris $VTRS sells hormonal generics. Theramex and Besins Healthcare are private specialists in women's hormonal medicines; Ferring is a private reproductive-medicine company; Fuji Pharma (富士製薬工業) in Japan and Acrux in Australia sell narrower menopause products. For Pfizer, Premarin is a small part of a large group; for Organon, women's health accounted for 28% of 2025 sales, or about $1.8bn.⁶ None separately discloses revenue tied to hormone testing.

Why a prescription never meant a blood test

For most conventional HRT, clinicians have not adjusted doses by chasing a laboratory number. They begin with a standard dose, select a route—a tablet, patch, gel or vaginal preparation—and adjust according to symptoms, bleeding, side effects, adherence and changes in risk profile.

The rationale for more testing is biologically plausible. Hormones are metabolised differently between patients; estradiol levels vary by route and timing; and symptoms can wax and wane. That makes test-guided dosing easy to imagine. But plausibility is not evidence that routine measurement improves care.

The labelling of an FDA-approved estrogen product states that serum FSH and estradiol levels have not been shown to help manage moderate to severe vasomotor symptoms.¹⁰ The UK's National Institute for Health and Care Excellence advises diagnosing menopause in otherwise healthy women over 45 from symptoms rather than laboratory tests.¹¹ The American College of Obstetricians and Gynecologists tells patients that hormone testing is generally unnecessary before starting hormone therapy.¹² For ordinary menopause care, the clinical case for routine test-guided dosing has not been established.

That boundary held even as regulators softened their view of some HRT risks. In February 2026, the FDA approved label changes for six menopausal hormone products that removed cardiovascular disease, breast cancer and probable dementia from their boxed warnings. It also noted that women who begin HRT within ten years of menopause onset, generally before age 60, have lower all-cause mortality and fewer fractures.¹³ The change concerned treatment eligibility and timing, not routine hormone testing.

Reproductive medicine, by contrast, created the first setting in which repeated hormone data changed the timing of an intervention that can cost tens of thousands of dollars.

↑ Back to Top

Fertility makes repeated information worth paying for

On 25 July 1978, Louise Brown was born in Oldham, near Manchester, the first person conceived through in vitro fertilisation. Her birth followed years of work by the Cambridge physiologist Robert Edwards, the Oldham gynaecologist Patrick Steptoe and the nurse and embryologist Jean Purdy.¹⁴ Edwards spent the 1960s studying how human eggs mature and can be fertilised outside the body; Steptoe developed the laparoscopic techniques used to retrieve eggs; and Purdy carried out much of the laboratory work. Their early efforts faced public hostility and were denied funding by the UK's Medical Research Council.¹⁵ Edwards received the Nobel Prize in 2010; Steptoe and Purdy had died by then.¹⁴

A decision loop, not a score

IVF changed the economics of monitoring because measurements inform expensive, time-sensitive clinical decisions. During a stimulation cycle, a patient takes injected hormones to grow several eggs at once. The clinic tracks the ovarian response through ultrasound scans and blood tests, then uses those results to adjust drug doses, time the injection that completes egg maturation and schedule egg retrieval. Too little response can waste a cycle; too much can cause ovarian hyperstimulation, a dangerous complication.

The hormones form a feedback system. FSH, or follicle-stimulating hormone, prompts the ovaries to grow follicles. Growing follicles release estradiol. An LH, or luteinising hormone, surge triggers ovulation, while progesterone prepares the uterine lining. AMH, or anti-Müllerian hormone, is produced by small follicles and provides a rough indication of remaining egg supply. No result stands alone: clinicians interpret it alongside the cycle day, scans, medications and the patient's history.

That is the distinction for the broader market. In fertility treatment, repeated measurement has value because it supports a costly, consequential decision under clinical supervision.

Outcomes become public

The United States made that accountability formal. The Fertility Clinic Success Rate and Certification Act of 1992 required clinics performing assisted reproductive technology, or ART, to report success rates, and the CDC began collecting the data in 1995.¹⁶¹⁷ Clinics then competed partly on published outcomes. In 2019, the latest year in the national summary Empor could rely on, US clinics reported 330,773 ART cycles.¹⁸ More recent national figures were not reliably available for this story.

Three different tollbooths

Each cycle supports a chain of suppliers, one of the few parts of hormone monitoring where company filings make clinical spending visible.

Drug makers supply stimulation hormones. Merck KGaA $MRK.DE, the German group, reported €1.5bn in fertility sales in 2025, about 7% of group revenue.⁶ Organon and the private company Ferring also sell fertility drugs. In China, Livzon Pharmaceutical (丽珠医药) reported CN¥1.4bn in reproductive-medicine revenue.⁶

Tool and consumables makers supply clinic laboratories. CooperSurgical, part of CooperCompanies $COO, sells fertility products and IVF-laboratory consumables alongside other women's-health products. Its wider CooperSurgical unit generated $1.3bn in fiscal 2025 revenue, including $525m from fertility.⁶ Sweden's Vitrolife reported SEK3.4bn in revenue from products including culture media, time-lapse incubators and genetic tests for IVF laboratories.⁶ Basecare (贝康医疗) in China supplies embryo genetic testing; Memphasys in Australia sells sperm-separation devices; and Femasys in the US reported $2.3m in sales from fertility diagnostics and treatment tools.⁶

Clinic operators provide the care itself. Hong Kong-listed Jinxin Fertility (锦欣生殖) reported 28,039 treatment cycles and a 2025 loss as revenue fell 8.2%.⁶ Monash IVF in Australia reported a 0.7% revenue decline in the year to June 2026.⁶

Merck, CooperSurgical and Vitrolife occupy different points in the chain: drugs, clinical workflow and laboratory technology. But the clinic controls the protocol and bears responsibility when a cycle fails. That responsibility helps explain why clinics pay for validated inputs.

Why IVF does not generalise easily

It is tempting to infer that, because repeated hormone data can guide IVF, they should be useful for everyone. The comparison does not hold. ART is unusually intensive, costly and closely supervised. A patient may have several blood tests and scans over two weeks, each linked to a decision about medication that can cost hundreds of dollars per vial. That model offers little evidence that daily measurements would improve care for uncomplicated menopause or make automated HRT dosing safe. Even in fertility, recent weakness among clinic operators shows that treatment volumes depend on affordability, policy and demographics as well as technology.

Consumer diagnostics would draw a different lesson from reproduction: the privacy and convenience of the pregnancy test, and the prospect of turning a once-a-cycle answer into a daily habit.

↑ Back to Top

From a blue line to a daily habit

In 1988, Unipath, then part of Unilever, launched Clearblue One Step, a pregnancy test that could be held in a urine stream and read within minutes.¹⁹²⁰ Its advance was as much in packaging as in science. The first Clearblue test, launched in 1985, required several steps; One Step reduced them to one.²¹ In 1989, Unipath applied the design to LH with Clearplan, an at-home ovulation test.²⁰ Home testing had moved from answering “am I pregnant?” to helping identify the most fertile time.

A paper highway

These tests use lateral flow. A strip of porous material, often nitrocellulose, acts as a paper highway: urine carries antibodies tagged with coloured particles along it. If the target hormone is present, it binds to the particles. The resulting complexes are caught by a stripe of fixed antibodies farther down the strip, producing a visible line. It is Yalow's antibody lock adapted to paper and sold through pharmacies.

The analogy has an important limit. A basic lateral-flow test usually provides a yes-or-no result around a threshold. It indicates that LH has reached a level associated with an imminent surge; it does not provide a full clinical picture.

From one line to many

Unipath's next product anticipated the business model used by newer entrants. Persona, launched in 1996, paired a handheld monitor with urine sticks that measured both LH and E3G, a urine breakdown product of estrogen, to identify fertile days for contraception.²⁰ A reader, recurring consumables and an algorithm remain the template.

Mira, founded in 2015, launched a home analyser in 2018 that reads urine test wands and reports numeric values rather than a line.²² Its menu now includes LH, E3G, PdG and FSH.²³ Inito, which operates in India and the US, uses a reader that clips onto a smartphone and a strip that measures several markers at once.²⁴ Oova, Proov, South Korea's Sugentech and China's Wondfo (万孚生物) offer variations on the model. Inito reported 27% revenue growth in the year to March 2025 and raised a $29m Series B, according to press reports compiled by Empor; the other private makers do not publish comparable figures.⁶

What the strip measures

One distinction should remain clear. E3G and PdG, or pregnanediol glucuronide, are metabolites excreted after the body processes estrogen and progesterone. They can show a useful pattern: estrogen rising before ovulation and progesterone rising afterward. But they are not estradiol or progesterone concentrations in blood. Hydration, time of day, kidney function and individual metabolism all intervene between a circulating hormone and the number displayed on a phone. Mira's documentation describes its values as urine hormone metabolites.²³

Scale against sophistication

The consumer market divides into two camps. Scaled retail brands include Church & Dwight $CHD, which sells First Response pregnancy and ovulation tests through US pharmacies, and Rohto Pharmaceutical (ロート製薬), which sells Dotest LH tests in Japan. Their advantages are shelf space, brand recognition and simplicity.

Reader-and-app companies pursue richer signals and recurring strip sales. Inito and Mira sell multi-marker testing; Oova and Proov pair narrower tests with coaching; kegg takes another route, measuring the electrical properties of cervical fluid, an indirect signal rather than a hormone assay.

For reader companies, the device sale introduces the customer; replenishment strips are the recurring purchase. The key commercial measures are undisclosed: strips bought by active users, customer retention, clinician referrals and whether clinicians use the data. Church & Dwight does not break out First Response in a way that reveals fertility-test economics.

The lab in the bathroom?

The strongest consumer claim is that multi-marker urine readers put a hormone laboratory in the bathroom. The evidence supports a narrower conclusion. These devices may improve fertility timing, their intended use. Nothing in the public record supports treating them as substitutes for validated blood assays, much less as systems for setting HRT doses. The lack of published retention data and clinical-outcome studies does not rule out a consumer opportunity. For now, it describes a timing aid paired with recurring consumables.

Meanwhile, software companies found that users could engage with a health app daily even when no hormone was measured.

↑ Back to Top

The app learns to predict what it cannot measure

In August 2018, the FDA granted marketing authorisation to Natural Cycles, a Swedish app, as a contraceptive method.²⁵ It was the first direct-to-consumer contraceptive app the agency had allowed. The app measured no hormone. Users took their temperature each morning and entered period dates; an algorithm identified days when they should avoid unprotected sex.²⁶

The founders treated fertility timing as a statistical problem: software, they argued, could estimate fertile days from noisy data more effectively than paper charts.

Reading the heating bill

The method relies on basal body temperature. After ovulation, rising progesterone increases resting body temperature by a few tenths of a degree. By tracking daily readings, an algorithm can infer retrospectively that ovulation has occurred and learn an individual's pattern over time. It is like estimating a building's heating schedule from its electricity bill: often useful, but indirect. Illness, alcohol, disrupted sleep and travel can alter a reading without a hormonal change.

The FDA's decision was narrow. It covered contraception, a defined use supported by clinical data on typical-use effectiveness, and included warnings that no contraceptive method is perfect.²⁵²⁶ Natural Cycles showed that a consumer protocol tracked over time could secure medical-device authorisation for a specific claim. It did not establish that health apps can make broader clinical decisions. The company continued to grow: revenue rose about 25% in 2025 to roughly SEK512m, according to figures compiled by Empor.⁶

The sensors join in

Wearables later automated temperature collection. Oura added period prediction to its ring in October 2021, using continuous overnight skin temperature.²⁷ Its Cycle Insights feature estimates cycle phase and ovulation from those signals.²⁸ Apple $AAPL added temperature-based retrospective ovulation estimates to the Apple Watch; Samsung added similar features to its watches and ring; and Garmin $GRMN offers cycle tracking through its Connect app. Flo, a private app, built a large consumer base around symptom and period logging.

None measures hormone concentration. But daily records of symptoms, bleeding, sleep, medication and behaviour may be more useful to routine care than a single inferred cycle phase. They can support reminders, triage and better-prepared clinical conversations well before they can support a choice of medicine.

Who holds what

Each player controls a different part of the consumer relationship. Natural Cycles has the clearest regulated protocol. Oura combines a device with subscription revenue: figures from its registration statement, compiled by Empor, show revenue growth of 123% in the year to September 2025, though Empor could not verify its absolute revenue.⁶ Apple and Samsung have installed bases in the hundreds of millions, while Flo has broad engagement. None discloses a recurring business that measures sex hormones.

Why prediction is not diagnosis

The broader claim—that algorithms will eventually do what assays do—is not supported by the record. An app can predict a fertile window or cycle phase without determining estradiol exposure, diagnosing an endocrine disorder or selecting an HRT dose. Even within its narrow indication, Natural Cycles' authorisation rests on typical-use failure rates: as with any contraceptive method, some users become pregnant, and effectiveness depends on behaviour as well as software.²⁶ Software authorisations are indication-specific; they do not transfer automatically to other medical uses.

That makes channel ownership more consequential than a dashboard alone. Hologic $HOLX sells mammography, cervical-screening and other women's-health diagnostics to clinicians. Its hormone-monitoring exposure is small, but its relationships with women's-health providers are extensive. Progyny $PGNY manages fertility and family-building benefits for US employers, converting coverage into clinic visits; it earned $1.3bn in revenue in 2025 at a net margin of 4.5%, consistent with the thin economics of a benefits manager rather than a software company.⁶ Both illustrate the recurring point: information has its greatest value when it can be translated into care.

The revival of the menopause market would test that proposition at scale, exposing the difference between a larger treated population and a larger monitoring market.

↑ Back to Top

Menopause returns, but the blood test does not become the prescription

On 31 May 2002, the independent board monitoring the Women's Health Initiative recommended stopping one of its central trials early.²⁹ The trial had enrolled 16,608 postmenopausal women aged 50 to 79 who still had a uterus and randomly assigned them to Prempro—a combination of conjugated equine estrogens and medroxyprogesterone acetate—or placebo.²⁹ The aim was to test whether HRT prevented heart disease and other chronic illnesses in healthy women. The National Institutes of Health launched the WHI in 1991 and began enrolling participants in its hormone trials in 1993.³⁰

After an average of about five years, women receiving treatment had more breast cancer, heart attacks, strokes and blood clots, but fewer hip fractures and colorectal cancers. The board concluded that, for prevention in this population, the risks outweighed the benefits.²⁹ Results published that July became global front-page news.

A reversal that set the standard

Few clinical studies reshaped a drug market as quickly. Prescriptions fell, patients stopped treatment, product labels acquired boxed warnings and many clinicians became reluctant to offer HRT. The women's-health drug market contracted, while a generation of doctors trained under the shadow of the WHI findings.

Later analyses made the picture more conditional. Many participants began treatment well after menopause, at an average age in their sixties, and outcomes varied by age, time since menopause and formulation.³⁰ The FDA's February 2026 label changes reflected that reassessment.¹³ But the WHI established a lasting standard for broad hormone-related claims: biological plausibility alone is not evidence of better outcomes. The same standard applies to monitoring.

The revival in numbers

England's dispensing data offer a clear measure of the return of menopause treatment. Pharmacies dispensed about 14.7m HRT items in the year to March 2025—11% more than a year earlier and more than triple the 4.5m items dispensed in 2018/19.³¹³² Most of the increase came after 2021, alongside public campaigns, celebrity advocacy, a cap on HRT prescription charges and intermittent supply shortages.

Dispensed items are not patients. They do not reveal dose changes, outcomes or hormone testing, and they reflect policy and supply as well as demand. They do show a larger treated population. Demographics reinforce the trend: women aged 50 and over accounted for 26% of women and girls worldwide in 2021, up from 22% a decade earlier, according to the World Health Organization.³³

The new care contest

The revival has attracted new providers. Private companies Midi Health and Evernow offer virtual access to US clinicians trained in menopause care. Hims & Hers $HIMS sells prescription treatments through subscriptions and has expanded its women's offering. Revenue rose 59% in 2025 to $2.3bn, but its operating margin was about minus 13% in the June 2026 quarter, and it does not disclose menopause revenue.⁶ Theramex and Besins specialise in women's hormonal drugs, while Bayer, Organon, Pfizer, Fuji Pharma and Acrux retain products and prescriber relationships.

The listed hormone-care group has not translated the revival into strong shareholder returns. Empor's combined figures show shares down 43% over the three years to September 2026, largely because diversified drug makers dominate the group and their valuations depend on businesses beyond menopause care.⁶ A growing treatment theme, in other words, has not created a focused public-market winner.

The decisive fact

For ordinary menopausal HRT, professional guidance does not recommend routine hormone tests to diagnose menopause in otherwise healthy women over 45 or to set treatment.¹¹¹² Care instead rests on symptoms, menstrual history, contraindications, route of administration, adherence, side effects and follow-up. That is the central constraint on any business built around HRT monitoring.

Testing still has defined clinical uses. NICE suggests FSH testing for women aged 40 to 45 with menopausal symptoms and changed periods, and for suspected premature ovarian insufficiency in women under 40.¹¹ Tests can help rule out thyroid disease and other causes of symptoms, investigate atypical cases, or assess specialist concerns such as possible poor absorption of a transdermal treatment. That supports a real but occasional, clinician-led testing market—not an established daily dose-monitoring market.

Can a test "optimise" HRT?

Some clinics and consumer brands market saliva, urine or blood panels as tools to “optimise” or “balance” hormone therapy. Hormone levels can vary between people taking the same dose. But proving that testing improves care would require a defined measurement, a prespecified treatment response and prospective evidence that test-guided changes improve symptoms, safety or adherence relative to usual care. No such evidence appeared in the public record reviewed for this story, and FDA labelling points in the opposite direction.¹⁰ The claim remains unproven.

Where HRT could still create a data business

Menopause care may still support valuable data businesses, but not necessarily through daily assays. Software can standardise screening for contraindications, track symptoms, prompt refills and adherence, coordinate pharmacy delivery, schedule follow-up and flag concerning bleeding. Those functions can improve the reliability of standard care without substituting a number for clinical judgement.

If routine care does not require a daily assay, the industry's more ambitious wager is to create an entirely new form of measurement.

↑ Back to Top

The sensor promise runs into the chemistry of the body

In January 2025, at the Consumer Electronics Show in Las Vegas, the Montreal start-up Eli Health showed Hormometer, a saliva test paired with a smartphone app for repeated at-home hormone readings, beginning with cortisol and progesterone.³⁴ A month later, UK start-up Level Zero Health announced a €6.6m pre-seed round to develop what it called the world's first continuous hormone-monitoring wearable, using DNA-based sensors.³⁵ Hormona, another young company, offers at-home hormone testing and symptom tracking. The idea of a hormone sensor had reached the market.

The glucose analogy

The comparison most often invoked is the continuous glucose monitor, or CGM. A small filament under the skin measures glucose in fluid between cells every few minutes and sends the reading to a phone. For people with diabetes, CGMs have changed care and created a substantial recurring-revenue business.

The analogy is useful but incomplete. A daily-use sensor with recurring disposable parts can be valuable. Yet glucose circulates at concentrations thousands of times higher than sex steroids, which may be present at picomolar to nanomolar levels, leaving far less signal for a sensor to detect. The sample also matters: saliva, sweat and interstitial fluid contain hormones in different amounts and with different delays from blood, and those relationships can vary with the menstrual cycle, medication and collection method. Most important, glucose readings inform an established decision: a person using insulin must decide how much to take. For menopausal HRT, clinical guidance does not identify an equivalent dose decision that a hormone reading should direct.

The engineering hurdles compound: calibration drift, proteins fouling a sensor surface, measurement lag and manufacturing yield. Each may be addressable in principle. Together, they help explain why hormone sensing has not yet been deployed at scale.

Repeated is not continuous

Two claims are often conflated. Eli's approach is repeated saliva testing, with samples collected when the user chooses. Level Zero proposes a wearable that would measure continuously. Neither description establishes accuracy or clinical usefulness. Eli's website describes its cortisol product as a wellness tool, not a substitute for laboratory testing.³⁶ That defines the product's current position.

What the benchmark businesses teach

Dexcom $DXCM shows what commercial success in continuous sensing can look like. The CGM maker reported $4.7bn in 2025 revenue, growth of 15.6%, a 60% gross margin and about 3.5m active users.⁶ Its operating margin reached 24% in the June 2026 quarter, six percentage points higher than a year earlier. Free cash flow has improved steadily, and the market values the company at 6.6 times sales.⁶ Senseonics, which makes an implanted glucose sensor, illustrates the more difficult path: it recorded $35m in 2025 revenue and losses of about twice that amount.⁶

Neither company makes a hormone sensor or has said it intends to. Their experience instead shows the sequence behind the CGM model: a defined clinical need, years of accuracy data, regulatory authorisation, clinician adoption and insurance coverage. Only then did hardware paired with recurring sensors become a high-margin business. Valuing an early hormone-sensor company against Dexcom assumes those steps have already been completed.

Investors may nevertheless be assigning value to the category. Empor's continuous-sensing layer, comprising Dexcom and Senseonics, returned about 28% in the year to September 2026, the strongest performance of any layer in the theme, although neither company sells a hormone product.⁶

Picks and shovels, and a lab in reserve

If low-level steroid measurement expands, the earliest beneficiaries may be suppliers of mass spectrometry and chromatography, including Waters, Agilent and Thermo Fisher. Reference laboratories would still be needed to confirm new sensor readings, much as blood-glucose meters remain part of CGM care. A consumer sensor could displace some routine repeat tests while also creating demand for confirmatory testing.

Promise against record

As of 25 September 2026, no broadly adopted, FDA-cleared continuous monitor for sex hormones had been identified in the agency's device resources.³⁷ That reflects a search result, not proof that no niche device exists. Earlier consumer-diagnostics efforts show that a technically plausible measurement can still fail on sampling, usability, clinical workflow, reimbursement or retention. Level Zero's funding demonstrates investor willingness to finance the attempt, not that the technology works.

The regulatory backdrop also remains unsettled. In May 2024, the FDA issued a rule bringing laboratory-developed tests under its device regulations. A federal court in Texas vacated the rule on 31 March 2025, and in September 2025 the agency restored its regulations to their previous text.³⁸ That leaves scope to develop tests within laboratories. It does not establish that any such test is accurate, clinically useful or safe for dose decisions.

Whether or not a sensor reaches the market, the existing owners of assays, sample collection, care protocols and medicines continue to collect most of the cash.

↑ Back to Top

Follow the sample, then follow the money

Follow a single blood sample. A woman in her early forties with irregular periods and hot flushes sees her doctor, who orders an FSH test and a thyroid panel to rule out other causes. A phlebotomist draws blood at a collection centre or, increasingly, at home. A courier takes the tube to a regional laboratory, where it is spun, barcoded and loaded onto an analyser using reagents supplied by the analyser's maker. The result enters the laboratory information system and the doctor's record. The doctor decides, the pharmacy dispenses, the insurer or patient pays, and a follow-up is booked. Each hand-off supports a different business.

Step one: the chemistry

Analytical validity is the gate. A wrong result undermines every decision that follows, helping to explain the durable position of owners of validated assays. Abbott, Roche, Siemens Healthineers and Beckman Coulter sell the automated immunoassay platforms that run most routine hormone tests. Revvity $RVTY has a diagnostics business with roots in reproductive and newborn health; it reported $1.4bn in diagnostics revenue in 2025.⁶ DiaSorin is the specialist. Sysmex in Japan, Mindray (迈瑞医疗) $300760.SZ and SNIBE (新产业生物) in China, and Fujirebio, part of Fujifilm $4901.T, compete with their own analysers and hormone menus. Waters, Agilent and Thermo Fisher support mass-spectrometry workflows. Wondfo is closer to low-cost point-of-care and fertility tests. bioMérieux $BIM.PA is primarily an infectious-disease diagnostics company and is relevant only as an adjacent laboratory supplier.

None discloses hormone-test revenue. For the largest groups, endocrinology is a small part of a broad test menu. In China, provincial volume-based procurement of diagnostic reagents affects prices, but public disclosure is too limited to quantify hormone-menu economics.

Step two: collection and testing

The second link is the laboratory network. Quest and Labcorp dominate the US. Sonic Healthcare $SHL.AX, based in Australia, operates pathology networks across Australia, Europe and the US. Eurofins Scientific $ERF.PA has a clinical-diagnostics arm alongside much larger food, environmental and pharmaceutical-testing operations. H.U. Group's SRL is a leading Japanese laboratory and is linked through its parent to Fujirebio. India has its own large chains: Dr. Lal PathLabs $LALPATHLAB, Metropolis Healthcare $METROPOLIS, Thyrocare Technologies $THYROCARE.NS, which began as a thyroid-testing specialist, and Vijaya Diagnostic Centre $VIJAYA.NS.

Their advantages are harder to replicate than a dashboard: collection networks, payer contracts, logistics, accreditation and years of patient results. Dr. Lal reported 7,727 patient service centres in its 2025-26 annual report.⁶

Step three and beyond: the result, the protocol, the medicine

The result must then reach someone able to act on it. Home-testing brands such as Everlywell and LetsGetChecked, and membership services such as Function Health, sell tests directly to consumers and send samples to partner laboratories; their revenue and repeat-use figures are not public. Clinics and telehealth providers turn results into decisions. Drug makers receive the prescription dollar.

Each link captures revenue differently. Platforms depend on reagent pull-through from tests run on their installed base. Laboratories depend on reimbursement, route density and test mix. Home-testing brands seek repeat purchases. Clinics and telehealth providers need patients to arrive, remain in care and fill prescriptions. Drug makers benefit from persistence on therapy. By revenue, prescriptions are the largest pool: Empor's hormone-care layer, dominated by diversified drug makers, had $116bn of combined revenue, compared with $33bn for listed clinical laboratories and $4.7bn for continuous sensing.⁶ Because those totals include substantial unrelated businesses, they show where larger cash pools sit rather than the size of hormone monitoring itself.

Who owns the patient's data?

It is tempting to picture one company holding the “whole patient.” In practice, the laboratory holds results, the app holds symptoms, the pharmacy holds fills, and the clinic holds diagnoses and outcomes. Privacy law, consent, incompatible systems and medical liability keep those records separate. A company that joins them lawfully and usefully could hold a valuable asset. No listed company in this theme has demonstrated that capability.

What the numbers say about each link

The laboratory link is growing. Empor's seven listed clinical laboratories increased combined revenue by 9.1% in the June 2026 quarter, and all seven reported growth.⁶ Quest grew 11.8% in 2025, generating $11.0bn in revenue and a 14.5% operating margin. Labcorp grew 7.2%, with $14.0bn in revenue and a 10.9% margin.⁶ Yet combined operating margin fell 6.4 percentage points from a year earlier, largely because of one-off movements at Sonic and Metropolis. Revenue growth, therefore, was not translating directly into profit.⁶

The Indian chains grew faster and generated higher operating margins. Vijaya reported a 30.1% operating margin in the year to March 2026, while Thyrocare reported 25.0%, compared with Quest's 14.5%.⁶ Investors have priced in that performance: Vijaya traded at 84 times earnings and Dr. Lal at 61 times, against roughly 25 times for Quest and Labcorp.⁶ Those valuations depend on Indian consumer-health spending and city-by-city network expansion, conditions specific to that market.

The assay link is less clear. DiaSorin, the listed platform most exposed to endocrinology, reported a 25.5% operating margin in 2025 but revenue growth of only 0.8%; its market value has fallen by about a fifth a year since 2022.⁶ QuidelOrtho, a broad-menu supplier, shrank and lost money, and was valued at $719m.⁶ Neither company provides a clean measure of hormone demand.

The chain that the data cannot yet see

In principle, the links should operate in sequence. More women using hormone treatment might lead, within a quarter or so, to more baseline and safety tests at laboratories; more testing might then lead to additional reagent sales for assay makers. Empor tested those links against reported results.⁶

The first relationship could not yet be tested because too little matched history exists. The second did not hold in the available data. DiaSorin's growth generally moved opposite to laboratory growth across eight periods, while QuidelOrtho showed a relationship only three quarters later than expected. Broad segment reporting, currency movements, the unwinding of pandemic testing and changing test mix probably swamp any hormone-specific signal. A few years of data are evidence, not proof, in either direction. The reasonable chain from hormone care to assay makers remains unproven in the reported numbers.

The important contests are therefore separate: laboratory scale, clinical integration, consumer habit and authority over the treatment protocol.

↑ Back to Top

Four contests decide whether daily care becomes a business

The market divides into four settings: laboratory procurement, fertility treatment, consumer testing and telehealth follow-up. Each has different customers, economics and measures of success.

The procurement meeting

A hospital or laboratory chooses an analyser and signs a multiyear reagent contract. Abbott, Roche, Siemens Healthineers and Danaher's Beckman Coulter compete through installed base, menu breadth, reliability and service. Their advantage lies in validated, high-throughput infrastructure for routine hormone tests, reinforced by the cost and disruption of switching platforms.

That does not make them pure hormone investments. Their diagnostics businesses are broad, and none reports hormone revenue. DiaSorin competes as a specialist with higher margins than many peers. QuidelOrtho illustrates the pressure on smaller broad-menu suppliers: revenue fell in each of the past three years, and its 2025 net loss equalled 41.5% of sales.⁶ The relevant measure is the volume of validated tests run on an installed analyser, which companies do not disclose for hormones.

The laboratory network

Laboratories compete for doctors' orders and payer contracts. Quest and Labcorp have US scale, national payer relationships and extensive collection networks. Sonic is the most geographically diversified. In India, Dr. Lal, Metropolis, Thyrocare and Vijaya compete through network density and preventive-health packages sold directly to consumers.

Geography shapes the contest. Quest and Labcorp remained profitable and grew combined revenue in each of the past two years; Empor's listed laboratory group rose about 46% over three years.⁶ Vijaya earned the layer's highest margin, while Metropolis grew fastest in its latest year, at 23.6%.⁶ Indian chains also trade at higher multiples, leaving their shares vulnerable to even a modest slowdown in growth. Direct-to-consumer testing could eventually weaken the patient relationship that large US laboratories hold through clinicians, though the evidence has not yet shown that shift at scale.

The treatment room

Fertility clinics choose the drugs and technology used in treatment. CooperSurgical, Merck KGaA and Vitrolife sell into settings where repeated measurement already changes clinical decisions. Jinxin and Monash earn revenue by providing care, while Basecare, Memphasys, Femasys and Livzon supply narrower technologies or medicines.

This is the part of the theme where measurement has the clearest link to spending, but recent growth has been weak. Jinxin's revenue fell 8.2% in 2025, and Monash's declined in its latest year.⁶ Fertility demand depends on affordability, public funding, regulation and birth-rate trends, and can be cyclical. The relevant measures are treatment-cycle volumes and clinic adoption of workflow tools tied to outcomes. Consumer-app downloads do not affect this market directly.

The bathroom and the follow-up call

The fourth contest has two parts. In the bathroom, Inito, Mira, Oova, Proov and Sugentech seek recurring strip sales, while Natural Cycles, Flo, Oura, Apple, Samsung and Garmin compete for daily attention. In the follow-up call, Midi, Evernow and Hims & Hers compete for the continuing clinical relationship and resulting prescription.

For consumer data to become a durable care business, users must reach an appropriate clinician and remain in treatment. A more detailed hormone chart is not enough. Retention data from consumer brands are limited; telehealth providers face customer-acquisition costs, clinician constraints and state-by-state regulation; and Hims & Hers' operating loss in 2026 showed how quickly growth spending can outweigh margins.⁶

What investors actually hold

Taken together, the four contests lead to a straightforward conclusion. No listed company in Empor's map reports a material, pure-play profit pool from daily sex-hormone monitoring. The companies most directly pursuing it—including Inito, Mira, Eli, Level Zero, Midi and Evernow—are private. Listed companies are exposed through infrastructure, care delivery or optional bets.

Valuation multiples cannot be compared as though a reagent supplier, laboratory, fertility clinic and consumer app shared the same economics. A new measurement could alter that hierarchy, but it would first need to prove that it improves a decision current care cannot already make.

↑ Back to Top

The future is not "more data"; it is a better decision

Picture two patients a few years from now.

The first buys a monthly hormone panel and a smart ring. Each week brings new charts. Her estradiol appears lower than it did last month, and her app flags the change in orange. She worries and books an appointment. Her doctor follows existing guidance and changes nothing because the result does not alter treatment. She has paid for data and gained anxiety.

The second is in her early forties, with irregular cycles and troubling symptoms. A validated home test, taken at the appropriate time, identifies a pattern suggesting early ovarian insufficiency. The result is routed to a clinician, who confirms it with a laboratory test and starts treatment months earlier than might otherwise have occurred. She has paid for data and gained a decision.

Both futures use similar technologies. The difference is the evidence and protocol surrounding the number.

The optimistic chain

In the bullish case, a low-friction assay or sensor matches reference performance in its intended fluid; detects something conventional care misses; and feeds a clinical protocol that specifies what to do with the result. Prospective studies then show better patient outcomes, and payers or consumers fund repeat use. Value could shift towards the owner of the validated sensor-plus-protocol, the data infrastructure and the clinical channel. Laboratories would retain confirmation work, while assay makers and mass-spectrometry suppliers would serve the additional demand.

The sceptical chain

In the bearish case, hormone fluctuations remain too dependent on context to guide routine care; menopause treatment remains symptom-led; frequent testing adds cost and noise; consumers churn; and sensors struggle to achieve accuracy and regulatory clearance. Value remains concentrated in clinical laboratories, fertility clinics, drug makers and care-access providers.

On current evidence, the more likely outcome lies between those cases: better digital workflows around existing tests and care, with home collection widening access but not automating dose decisions.

Four beliefs worth testing

Several popular beliefs do not survive contact with the evidence.

The first is that a urine fertility tracker measures HRT exposure. It measures urine metabolites such as E3G and PdG, which can reveal cycle patterns in people who are still cycling. The relationship between those metabolites and blood levels of estradiol taken as a patch or gel has not been validated as a dosing guide.

The second is that more individual data automatically produce more personalised medicine. Personalisation requires a validated rule for acting differently on a given result. Without one, more data create more variation to explain and a greater risk of acting on noise.

The third is that glucose monitoring's success establishes a clinical indication for hormone monitoring. CGM supported a decision that people with diabetes already made several times a day. A hormone sensor must first establish the decision it improves.

The fourth is that rising HRT prescriptions prove rising demand for hormone tests. England's HRT dispensing more than tripled while guidance continued to discourage routine testing for most women over 45.³¹¹¹ Treatment and testing can therefore grow at very different rates.

What would change the map

Several developments could redraw the economics: a regulator-cleared continuous sensor for a precise medical indication; a published trial showing that a monitoring protocol improves symptom control, safety, adherence or fertility outcomes; insurance coverage for repeat testing; disclosed cohorts showing repeat purchases; or a trusted integration of laboratory results, prescriptions and outcomes.

The less glamorous opportunity

A nearer opportunity requires none of those breakthroughs. Software that standardises care pathways—from screening questionnaires to follow-up reminders and escalation rules—can make existing care more consistent without claiming to set doses. Employers funding fertility and menopause benefits, benefits managers such as Progyny, telehealth providers and clinical networks could capture that value first. It would not resemble a sensor windfall, but it may prove more durable.

These developments should appear in a handful of signals well before they register as broad revenue growth.

↑ Back to Top

The signals that settle the argument

Revenue will be the last place the answer appears. By the time a hormone-monitoring profit pool reaches company accounts, the question will probably have been settled elsewhere. Five earlier signals matter.

A cleared sensor with a job to do

The first is an FDA-cleared continuous sex-hormone monitor with a defined medical indication. That would show that sensing had crossed both regulatory and analytical thresholds. Clearance normally precedes adoption by years, and would distinguish a potential clinical platform from a wellness product. The FDA publishes device decisions in its databases as they occur.³⁹ As of September 2026, Empor had identified no broadly adopted example. A clearance with a published decision summary and specific intended use would strengthen the sensor case; no credible validation progress by the end of 2028 would weaken its near-term version.

Proof that repeated measurement helps

The second is prospective outcome evidence: a controlled study showing that a protocol based on repeated measurement improves symptom relief, safety, adherence or fertility outcomes compared with usual care. Such evidence would appear irregularly in trial registries and peer-reviewed journals. It would establish whether the category is clinical or simply more convenient. No broadly comparable evidence across companies had been identified. Repeated studies showing no added benefit would leave the category largely in wellness.

England's HRT dispensing

The third is England's HRT dispensing, published annually by the NHS Business Services Authority.³² It measures treatment activity before it appears in company sales. The latest reading was about 14.7m items in the year to March 2025. Sustained growth after supply shortages ease would support the view that care demand is structural. It would not, by itself, establish demand for testing; a multi-year decline would weaken the care-demand case.

The low-estradiol bar

The fourth is performance against the CDC's hormone standards. The CDC's certification criterion for estradiol permits bias of no more than 2.5 pg/mL at concentrations at or below 20 pg/mL, and 12.5% above that; for testosterone, the allowance is 6.4%.⁴⁰ The programme reports certified methods on a rolling basis. Any new assay or sensor claiming clinical relevance should publish a transparent comparison in its own sample type near that bar. Unexplained bias, drift or the lack of an independent comparison would weigh heavily against it.

Repeat use and hand-offs to care

The fifth is the number of strips or tests an active user buys, and the share of users referred to and retained by a clinician. Those measures distinguish a recurring consumer business connected to care from a one-cycle purchase. Private tracker brands do not disclose them, and no company reports them quarterly. Cohorts showing consistent replenishment and appropriate referrals would support the business model; continued silence would leave it unproven.

Watch these signals. The first company to capture a genuine daily-care profit pool may not be the first to display a hormone number.

↑ Back to Top

The owner of the protocol gets paid

Rosalyn Yalow and Solomon Berson made hormones measurable. The remaining question is what a clinician or patient should do with the result.

If monitoring moves from occasional testing to daily care, durable profits are most likely to go to companies that combine reliable measurement, recurring consumables or testing capacity, a route to patients and a validated protocol for action. Today, that description fits established laboratory infrastructure and fertility treatment, where repeated measurements already guide costly decisions. It could eventually describe a company that combines a validated sensor with clinical care. None has yet demonstrated that model.

For HRT, more treatment does not necessarily mean more testing. Drug makers, clinicians, telehealth providers, pharmacies and follow-up software can benefit from expanding menopause care without creating a daily hormone-monitoring market. Current regulatory and professional guidance does not make frequent consumer hormone testing necessary for standard HRT care.¹¹¹²¹³ A business premised on the opposite is betting on evidence that has not yet been produced.

The eventual winner will not be the company that displays the most data. It will be the one that proves its data improve a decision that patients, clinicians and payers value.

↑ Back to Top

Glossary

• Antibody: a protein that recognises a specific target molecule; assays use that recognition to detect hormones.
• AMH: anti-Müllerian hormone, produced by small ovarian follicles and commonly used to estimate ovarian reserve.
• ART: assisted reproductive technology, including IVF.
• Assay: a method that turns a biological sample into a reported result.
• E3G: estrone-3-glucuronide, a urine metabolite of estrogen; not the same as estradiol in blood.
• Estradiol: the principal circulating estrogen, measured in reproductive and endocrine settings.
• FSH: follicle-stimulating hormone, which signals the ovaries to grow follicles.
• HRT/MHT: hormone replacement therapy, or menopausal hormone therapy; distinct from contraception and fertility drugs.
• Immunoassay: an antibody-based method for measuring a substance in a sample.
• LC-MS/MS: liquid chromatography-tandem mass spectrometry, a selective method used in specialist and reference hormone testing.
• LH: luteinising hormone, whose surge signals that ovulation is approaching.
• PdG: pregnanediol glucuronide, a urine metabolite of progesterone.
• Reagent pull-through: recurring sales of tests, chemicals and consumables after an instrument is placed.
• Reference method: a highly accurate method used to assess or calibrate routine tests.
• Vasomotor symptoms: menopause-related hot flushes and night sweats.

References

1. Rosalyn Yalow — Nobel Prize Outreach, Women who changed science ↩↩↩

2. Radioimmunoassay: a probe for fine structure of biologic systems, Nobel lecture — Rosalyn S. Yalow, Nobel Prize Outreach, 1977 ↩↩

3. Challenges to the measurement of estradiol: an Endocrine Society position statement — Journal of Clinical Endocrinology & Metabolism, via PubMed Central, 2013 ↩

4. Hormone Standardization Program — US Centers for Disease Control and Prevention ↩↩

5. CDC project on standardizing steroid hormone measurements — Steroids, via PubMed, 2008 ↩

6. Hormone Monitoring theme data: scorecard, pulse, trends and links tables, from company filings and market data via Eulerpool — Empor, 25 September 2026 ↩↩↩↩↩↩↩↩↩↩↩↩↩↩↩↩↩↩↩↩↩↩↩↩↩↩↩↩↩↩↩↩↩↩↩

7. Drug therapeutics and regulation in the US, FDA history exhibit — US Food and Drug Administration ↩

8. Enovid approval history — US Food and Drug Administration ↩

9. Premarin (conjugated estrogens tablets) prescribing information — US Food and Drug Administration, 2014 ↩

10. Estrogen product prescribing information (application 021367) — US Food and Drug Administration, 2023 ↩↩

11. Menopause: identification and management (NG23), recommendations — National Institute for Health and Care Excellence ↩↩↩↩↩

12. Do I need hormone testing before hormone therapy? — American College of Obstetricians and Gynecologists ↩↩↩

13. FDA approves labeling changes for menopausal hormone therapy products — US Food and Drug Administration, 12 February 2026 ↩↩↩

14. The Nobel Prize in Physiology or Medicine 2010, press release — Nobel Assembly at Karolinska Institutet, 2010 ↩↩

15. Scientific background: the development of in vitro fertilization — Nobel Assembly at Karolinska Institutet, 2010 ↩

16. Assisted reproductive technology surveillance, United States — CDC Morbidity and Mortality Weekly Report, 2020 ↩

17. National ART Surveillance System — US Centers for Disease Control and Prevention ↩

18. 2019 Assisted Reproductive Technology Fertility Clinic and National Summary Report — US Centers for Disease Control and Prevention ↩

19. Thin blue line: the history of the pregnancy test — National Institutes of Health, Office of NIH History ↩

20. Corporate venturing: the origins of Unilever's pregnancy test — Harvard Business School ↩↩↩

21. Pregnancy test history 101 — Clearblue ↩

22. Mira launches a device for more accurate fertility testing in the home — TechCrunch, 6 September 2018 ↩

23. What fertility hormones does Mira measure? — Mira help centre ↩↩

24. About Inito — Inito ↩

25. De Novo decision DEN170052, Natural Cycles — US Food and Drug Administration, 2018 ↩↩

26. FDA allows marketing of first direct-to-consumer app for contraceptive use to prevent pregnancy — Natural Cycles via PR Newswire, August 2018 ↩↩↩

27. Oura's latest fitness ring adds period tracking — Axios, 26 October 2021 ↩

28. Cycle Insights — Oura help centre ↩

29. Risks and benefits of estrogen plus progestin in healthy postmenopausal women: principal results from the Women's Health Initiative randomized controlled trial — JAMA, via PubMed, 2002 ↩↩↩

30. Women's Health Initiative (WHI) — National Heart, Lung, and Blood Institute ↩↩

31. Hormone replacement therapy, England, April 2015 to June 2025 — NHS Business Services Authority ↩↩

32. Hormone replacement therapy, England, summary to June 2025 — NHS Business Services Authority ↩↩

33. Menopause, fact sheet — World Health Organization ↩

34. Hormometer, CES Innovation Awards 2025 honoree — Consumer Technology Association ↩

35. Level Zero Health lands €6.6 million for world's first continuous hormone monitoring device — EU-Startups, February 2025 ↩

36. Eli Health product site — Eli Health ↩

37. Medical devices that incorporate sensor-based digital health technology — US Food and Drug Administration ↩

38. Laboratory developed tests — US Food and Drug Administration ↩

39. Find all FDA-approved home and lab tests — US Food and Drug Administration ↩

40. Improving performance: CDC Hormone Standardization Program — US Centers for Disease Control and Prevention ↩