Higher cumulative doses of common fertility drug clomiphene citrate may increase pregnancy loss risks, according to new research.

Around one in six people experience infertility, with irregular or absent ovulation among the most common causes.

Clomiphene citrate has long been a mainstay of fertility treatment, but Adelaide University research has raised concerns about higher cumulative doses.

The new study found that high doses of clomiphene citrate accumulated over multiple fertility treatment cycles could increase the risk of pregnancy loss.

Lead author associate professor Sheree Boulet said the findings showed a clear dose-response relationship, meaning the risks increased as cumulative exposure rose.

She said: “Women who received higher cumulative doses of clomiphene citrate experienced progressively greater risks of adverse pregnancy outcomes.

“We examined more than 21,000 embryo transfer cycles across four cumulative dose categories and found that increasing the dose did not significantly improve the chance of a live birth.

“Our findings suggest there may be a point where increasing the dose offers little additional benefit while exposing women to greater risk, highlighting the importance of carefully balancing effectiveness with safety when making treatment decisions.”

Supported by the NHMRC and conducted in partnership with Boston University and the Centers for Disease Control and Prevention, researchers analysed 21,004 IVF embryo transfer cycles in the US.

Women receiving cumulative doses of 500mg to 749mg of clomiphene citrate had a 12 per cent higher risk of miscarriage, while those receiving 750mg to 999mg had a 38 per cent higher risk.

Women receiving cumulative doses of 750mg or more were also more than twice as likely to have twins or other multiple births.

Rates of spontaneous abortion, another term for miscarriage, increased as the dose rose.

Researchers also recorded more than a threefold increase in stillbirth at the highest dose, although the finding was not statistically significant because that dose was rare. Larger studies are needed to confirm the association.

The finding is consistent with an earlier Adelaide University study that showed a doubling of neonatal death in pregnancies involving clomiphene citrate. Neonatal death means the death of a baby shortly after birth.

Higher cumulative doses did not improve the chance of a live birth, but did increase twinning, which raises the risk of adverse outcomes for both mother and child.

Clomiphene citrate is one of the world’s most widely prescribed fertility drugs. It has been prescribed to millions of women worldwide since 1967 and remains a recommended first-line treatment for ovulation induction.

The drug is recognised as an essential medicine by the World Health Organization. It works by stimulating the ovaries to release eggs, increasing the chance of pregnancy.

Women who do not respond to lower doses, or who require multiple treatment cycles, may receive progressively higher cumulative doses over time.

The findings build on a series of studies from Adelaide University’s Robinson Research Institute linking clomiphene citrate with increased risks of pregnancy loss, stillbirth, perinatal death and some birth defects.

Experimental studies in mice supported these findings, showing that higher doses reduced successful pregnancies and were associated with pregnancy loss, impaired fetal growth and developmental abnormalities.

Professor Michael Davies, senior researcher and co-author of all the studies, said the latest work builds on more than two decades of Adelaide-led research into the safety of fertility treatments.

He said: “Clomiphene citrate has been used by many women since 1967, but it has never been comprehensively evaluated in large prospective clinical trials.

“Our studies indicate that women respond differently to clomiphene citrate and that increasing cumulative doses may increase the risk of adverse pregnancy outcomes without improving the likelihood of a live birth.

“The findings confirm and extend our previous studies in both human and mouse models which highlight the need to better understand the dose-response relationship and whether more personalised dosing strategies could improve safety.

“Until we can better understand these differences, it remains important that clinicians rigorously follow manufacturer’s safety recommendations and avoid unnecessarily increasing cumulative doses.

“The same questions are now being asked of newer ovulation-inducing medications, so any move away from clomiphene citrate should also be guided by robust evidence rather than assumptions about safety.”

Women’s Health Week Europe 2026 has released its fully populated speaker and session lineup ahead of the event’s return to The Emirates Stadium in London on 7–8 October, with 80+ speakers now confirmed across two dedicated stages.

The programme

The agenda runs across two dedicated stages in parallel, plus two pitch competitions across both days.

The Global Stage opens with a keynote from Merete Clausen (EIF) before moving into sessions on funding trends, AI, the gender data gap, the wearable revolution, and European policy.

Standout sessions include The Age of Digital TransformAItion featuring Nichole Young-Lin (Google), Frida Polli (MIT), and Sapna Shah (Sie Ventures); Lone Wolf or Pack Leader on collaboration versus fragmentation, with Eirini Rapti (Inne), Tatum Getty (Thena Capital), Novo Nordisk, and Jen Roberts-Woods (Borski Fund); and a live debate on whether the women’s health label helps or hinders founders. Day one closes with a keynote from Alison Cave, Chief Safety Officer at the MHRA.

The Scale Stage runs a practical playbook track in parallel, with sessions covering regulatory approval pathways, international expansion, the founder’s legal playbook, PR strategy, and implementing AI into a women’s health business.

The Reverse Pitch flips the usual format: investors and corporates pitch the room on what they are actively looking to fund, acquire, or partner on right now.

View the full agenda and speaker lineup

Pitch competitions

The WHW Europe pitch competitions are back, taking place in front of the audience across both days on the mainstage. 16 finalists will compete across two categories: Consumer & Tech on day 1 and Medical Devices & Therapeutics on day 2.

Any company treating a condition that affects women exclusively, differently, or disproportionately is eligible to apply.

Applications and close 28 August 2026.

Previous alumni include Circe, who secured £100k from Innovate UK, BoobyBiome, who closed a £2.5M seed round post-WHW Europe, and Amilis, who secured £1M at London Tech Week after winning at WHW USA 2026.

Apply to pitch

UK femtech investment has risen by more than 194 per cent over the past decade, with deal activity and funding both increasing, new research has found.

The number of deals increased from 18 in 2015 to 53 in 2025, while total funding rose from £9.4m to more than £100m over the same period.

Despite the growth, deal volume and value remain relatively low compared with other parts of the health and care market. Healthcare recorded 69 deals in 2015 and 171 in 2025.

More companies have raised funding over the past decade, while investment values have also increased. Average deal size more than doubled from £527,000 in 2015 to £1.9m in 2025.

Some of the largest funding rounds last year included SheMed at more than £37m, Gaia at £12m, emm at £6.8m and Hertility at £5.9m, with the majority of investors based in the UK.

The research found femtech remains largely early-stage, with seed investments accounting for most deals.

However, venture capital involvement has increased over the past decade, which the research said showed the market was becoming more mature. The number of VC deals rose by 600 per cent.

Vicky Protano, corporate partner at Mills & Reeve, which conducted the research, said: “Over the last decade, the UK femtech ecosystem has expanded, both in terms of deal activity and funding levels. This positive upward trend demonstrates growing investor confidence in femtech and increasing institutional interest in the sector.

“Whilst companies in femtech have relied heavily on angel investors and angel networks to fund their growth ambitions, dynamics are shifting, with more venture capital and PE investors appearing in funding rounds. However, this is just the beginning and there is still more to do. While the sector has experienced strong growth, more work needs to be done to create the right funding environment that is balanced and evenly spread across the UK.”

The research found most deals had taken place in London. While the capital has strengthened its position as the UK’s main hub for femtech start-ups, regional clusters are gradually emerging elsewhere.

Protano said: “Whilst London clearly remains a dominant location for women’s health businesses and investment – both in terms of deal activity and total funding – there is a gradual move to regional expansion outside of the capital, with the South West, South East and the East of England showing increased investment activity in the femtech sector. What the data also highlights is a growing North/South divide, with areas such as the North East, North West, and Yorkshire & Humber significantly underrepresented in the national figures.

“As a national firm, we are also witnessing that similar divide. More investments are being made into women’s health businesses based in the South – and more businesses are, often as a result, locating themselves there, rather than in the North. This is representative of the investment landscape as a whole. However, growth in the femtech sector is being supported by growing regional innovation hubs, the increasing influence of university spin-outs, as well as improved support for start-ups at a regional level.”

She added: “Looking at the positives, we have advised and are continuing to advise on some significant investments in the sector. This further evidences the growing nature of femtech, with sector specific investors also coming to the market.”

Examples include Northern Gritstone’s investment in IVF technology business IVF Micro and Phoenix Private Equity’s investment in London Gynaecology, a provider of private gynaecology clinics.

Other deals include an EKA Ventures-led investment in tech-enabled postnatal care company Hesta Health and Amulet Capital’s acquisition of TFP Fertility.

September marks 10 years since the term “femtech” was coined by Ida Tin, co-founder and chief executive of Clue, one of the first period-tracking apps for women, and founder of think tank Femtech Assembly.

The global market grew to US$9.12bn in 2025 and is projected to reach US$41.4bn by 2034.

Despite that growth, women’s health is still not treated as a priority and significant gender inequalities remain globally in research, trials, diagnosis and treatment, continuing to disadvantage women.

Tin said: “I want men with money and power to get femtech on their radar. The business opportunity is there. The societal economic argument is there.”

Charlotte Lewis, commercial health lawyer at Mills & Reeve who specialises in healthtech and women’s health, said: “For far too long, ongoing disparities in women’s healthcare across the UK have adversely impacted women’s health outcomes, often resulting in prolonged diagnosis and treatment – some of which are well publicised, including the time it takes to diagnose women’s health issues such as endometriosis and rising maternal mortality rates.

“However, we are seeing the landscape beginning to shift in a more positive direction. Our experience is that this is helped by more open discussion and conversations which highlight the issues.

“The data around the sector is valuable and growing and demonstrates the progress that is being made from an investment point of view, creating a better environment where digital innovation can thrive, with a renewed focus on prevention through market-leading consumer-driven products.

“The UK has a real opportunity to transform women’s healthcare into a model of fairness, accessibility, and excellence, and femtech businesses have a crucial part to play in achieving this transformation. As a firm, Mills & Reeve is passionate and dedicated to continuing to influence and support this transformation.”