IVF NewsNews: Ultra-processed foods and fertility: what a new human study suggests before conception
IVF.net Newsdesk 31 March 2026
A growing body of reproductive research is asking a broader question than whether diet matters in pregnancy. It is asking whether the food choices made by both partners before conception may already be shaping fertility and the earliest stages of embryonic development. A new study in Human Reproduction adds an important piece to that picture by linking higher intake of ultra-processed foods, or UPFs, with lower fertility in men and with subtle differences in early embryonic growth in women. The study came from the Generation R Study Next Programme in the Netherlands and included 831 women and 651 male partners who were followed from the preconception period or early pregnancy onward. Researchers assessed diet during early pregnancy, at a median of about 12 weeks, using a detailed food-frequency questionnaire. They then classified foods by the degree of processing and expressed UPF intake as a percentage of total food intake by grams per day. Median UPF intake was 22 percent for women and 25 percent for men. Fertility outcomes were assessed through time to pregnancy, fecundability, and subfertility, while embryonic development was measured by transvaginal ultrasound at 7, 9, and 11 weeks of gestation. What makes this paper especially interesting is that it looks at both sides of the couple at once. Reproductive medicine has often placed the weight of preconception health on women, but this study deliberately examined maternal and paternal diet together. That matters because conception is a shared biological process, and the quality of sperm, the uterine environment, and the metabolic context around implantation all contribute to what happens next. The central finding was a sex-specific pattern. Higher paternal UPF consumption was associated with reduced fertility, including decreased fecundability and a higher risk of subfertility. In practical terms, couples in which the male partner consumed more UPFs tended to take longer to conceive. By contrast, higher maternal UPF intake was not consistently associated with time to pregnancy, but it was associated with slightly smaller embryonic growth and smaller yolk sac volume, particularly early in the first trimester. The yolk sac is a small but essential structure in early pregnancy, helping support the embryo before the placenta fully takes over. These developmental differences were small, and the authors are careful not to overstate them. This is an observational study, so it does not prove that UPFs directly caused the fertility changes or the altered growth patterns. But the results are still notable because early embryonic growth has been linked in prior work to later outcomes, including preterm birth and lower birth weight, while abnormal yolk sac development has been associated with miscarriage risk and other complications. Small shifts in early development may therefore matter even when they look modest on the ultrasound screen. The paper also raises an important mechanistic question. Why might paternal diet show up more clearly in fertility measures, while maternal diet appears more closely tied to early embryonic growth? One likely explanation is timing and route of influence. Sperm may be especially vulnerable to poor diet quality through effects on production, motility, integrity, and oxidative stress. Maternal diet, meanwhile, may act more directly through the environment in which the embryo develops from the very start, including nutrient availability and the biology of the yolk sac. The authors also note that UPFs may not be acting through poor nutrition alone. Additives, packaging-related exposures, and microplastics remain plausible candidates that deserve closer study. There is another reason this study deserves attention. The Dutch cohort had relatively modest UPF exposure compared with countries such as the United States and the United Kingdom, where UPFs can account for about half of daily intake. Even in this population, the associations were detectable across the full range of intake. That means the findings may have broader implications in settings where processed foods make up a much larger share of the diet. For IVF professionals and reproductive scientists, the paper is less a call for alarm than a call for precision. It adds to a larger shift in thinking about preconception care. Instead of focusing narrowly on maternal behavior after pregnancy begins, the field is moving toward a couple-based view of reproductive readiness. Diet quality before conception may be one more variable that influences how quickly pregnancy is achieved and how robustly the embryo develops in its earliest days. It is also a reminder that not all dietary risk is dramatic or obvious. Ultra-processed foods are often not a single category of indulgence but a routine part of modern eating: packaged breads, sweetened drinks, ready meals, processed snacks, and highly formulated convenience foods. Their ubiquity makes them difficult to study cleanly, but also highly relevant. When a signal appears despite that background noise, it is worth taking seriously. The most responsible interpretation is a measured one. This study does not mean that eating UPFs causes infertility, nor does it define a fertility-safe threshold. But it does strengthen the case for discussing diet as part of preconception counseling for both partners. In reproductive medicine, small influences accumulated across time can become clinically meaningful. The possibility that everyday dietary patterns could shape sperm-related fertility on one side and early embryonic development on the other is exactly the kind of finding that deserves careful follow-up. Sources 24 March 2026. Focus on Reproduction 24 March 2026. Human Reproduction 24 March 2026. The Independent 23 March 2026. Newsweek 26 March 2026. News Medical Life Sciences 24 March 2026. Everyday Health [ Full Article ]  
News: Sperm storage, abstinence, and the quiet biology of decline
IVf.net 31 March 2026
A new study from researchers at Oxford brings fresh clarity to a question that has long sat in an uneasy space between reproductive biology, clinical habit, and common sense: what happens to sperm when it simply waits. The answer, according to a large meta-analysis spanning humans and a wide range of non-human animals, is that storage itself appears to come at a cost. Across species, mature sperm tends to deteriorate while in storage, whether that storage happens in the male reproductive tract before ejaculation or, in some animals, within the female reproductive tract before fertilization. The paper, published in Proceedings of the Royal Society B, examines 115 human studies involving 54,889 men, alongside 56 studies across 30 non-human species. That breadth matters. Reproductive medicine often treats human semen parameters as a self-contained clinical domain, but this analysis places human sperm biology inside a much larger evolutionary pattern. The underlying message is straightforward: sperm cells are not static. Once mature, they are biologically vulnerable, and time in storage appears to expose that vulnerability. In men, longer abstinence was associated with higher oxidative stress and greater DNA damage, together with reductions in motility and viability. Those findings are especially interesting because they cut against a very familiar instinct in male fertility work, namely that more time without ejaculation should naturally produce a better sample. Quantity may rise with abstinence, and in many contexts semen volume and total count do increase, but the new analysis suggests that this gain can be accompanied by a measurable decline in aspects of sperm quality that are deeply relevant to fertilization biology. This does not mean that every shorter abstinence interval is automatically better, nor does it erase the practical trade-off between sperm number and sperm function. In fact, one of the most useful aspects of the new work is that it pushes the conversation away from one-size-fits-all thinking. The question is no longer simply how to maximize the amount of sperm in a specimen. It is how to balance count, motility, viability, and DNA integrity for the clinical purpose at hand. That balance may not look the same in conventional semen analysis, IUI, IVF, and ICSI. News coverage of the study reflects this same nuance, noting that longer abstinence can increase sperm quantity even as it may impair performance-related parameters. One of the strongest conceptual contributions of the paper is the framing of ejaculates as dynamic populations rather than uniform collections of identical cells. Sperm age. They accumulate damage. They differ in resilience. Some die sooner than others. That means semen quality is shaped not only by how sperm were made, but also by what happened to them after spermatogenesis was complete. This matters because post-meiotic sperm senescence has often sat in the background of reproductive thinking, acknowledged in principle but rarely placed at the center of clinical interpretation. The new study does exactly that. The animal data make the story even more compelling. In non-human species, sperm storage was linked not only to poorer sperm performance but also to reduced fertilization success and lower embryo quality. That broadens the relevance of the work beyond male factor semen assessment and into early development itself. If sperm storage influences embryo quality across species, then the biology of ageing sperm may be doing more than altering the probability of sperm reaching the oocyte. It may also be shaping what happens after fertilization. At the same time, the human evidence deserves careful reading. The Newsweek report on the paper highlights an important caution from the researchers: while human sperm quality declined with longer storage, the effects in men were statistically significant but modest, and the analysis did not show consistent evidence of reduced fertilization rates or poorer embryo quality in humans. That distinction is important. It suggests that biological deterioration is real, but its clinical translation in humans may be buffered by selection processes, laboratory techniques, or the fact that the most compromised sperm are less likely to succeed in the first place. This is precisely where the paper becomes most interesting for IVF. Assisted reproduction changes the path sperm must travel, but it does not make sperm biology irrelevant. In conventional IVF, the overall characteristics of the sample still matter. In ICSI, the laboratory intervenes much more directly, yet DNA integrity, oxidative injury, and the hidden burden of sperm ageing remain important considerations even when a single sperm is chosen under the microscope. The study does not hand clinics a fixed new abstinence rule, but it does argue persuasively that the upper end of traditional abstinence guidance may deserve renewed scrutiny. Oxford’s summary notes that current WHO guidance commonly recommends 2 to 7 days of abstinence before semen collection, while the new findings suggest that seven days may often be longer than ideal. There is also an intriguing technological angle. The study found that females in many species appear better than males at preserving sperm quality over time. That points toward evolved protective mechanisms within female reproductive storage environments, potentially including antioxidant-rich fluids and specialized storage structures. For reproductive scientists, this is more than a zoological curiosity. It raises the possibility that future sperm handling and storage methods could borrow from those natural models. Biomimetic approaches to semen preservation, antioxidant support, and microenvironment design may eventually become part of the practical legacy of this kind of comparative work. What makes this paper especially satisfying is that it does not simply tell clinicians to throw out familiar routines. Instead, it reframes the problem with better biology. Storage is not neutral. Time is not free. Mature sperm cells are exposed to ongoing biochemical wear, and that wear has measurable consequences. For the fertility field, that means abstinence interval should be treated less as a fixed administrative requirement and more as a biological variable. It also means that semen quality should be interpreted with a sharper awareness that the clock starts ticking long before the sample reaches the lab. In the end, this study does something valuable for both science and clinical practice. It narrows the gap between evolutionary biology and reproductive medicine. It reminds us that sperm cells are living, aging entities rather than passive carriers of paternal DNA. And it suggests that one of the simplest variables in andrology, the time between ejaculations, may deserve more thoughtful attention than it has received for many years. Sources 25 March 2026. University of Oxford 25 March 2026. Proceedings of the Royal Society B: Biological Sciences 25 March 2026. Mirage News 24 March 2026. Newsweek [ Full Article ]
News: RBMO Live 15: Fertility in Freefall
International IVF Initiative 16 March 2026
Session 168: RBMO Live 15: Fertility in Freefall17th March, 3pm EST, 7pm UK, 8pm CET Hosts: Prof. Nick Macklon and Prof. Bart Fauser Presenters: Prof. John Aitken: Declining global fertility and Prof. Adam Balen: The role of Fertility Education in addressing falling fertility rates Q and A Prof. Nick MacklonProf. Nick Macklon is Group Medical Director of LWC, LEB and LSB.
Prof. Bart Fauser Bart CJM Fauser, MD, PhD, FRCOG, is a Professor Em. of Reproductive Medicine, Gynecologist, former Head of the Department for Reproductive Medicine and Gynecology and former Chair of the Division of Woman & Baby at the University of Utrecht and the University Medical Center Utrecht, The Netherlands. He is the scientific director of the International Federation of Fertility Societies (IFFS), international member of the US National Academy of Medicine (NAM), member of the Academia Europea, Honorary member of European Society of Human Reproduction and Embryology (ESHRE), Fellow ad Eundum of the Royal College of Obstetrics and Gynaecology (RCOG), Honorary member of the Middle East Fertility Society (MEFS), Night in the order of the Netherlands Lion, consultant and advisory board member of a multitude of companies. He is a past member of the board of the Dutch Medical Research Counsel (ZonMW), past chair of the World Health Organization (WHO) steering committee for infertility guidelines, past Editor-in-Chief of Reproductive Biomedicine Online (RBMO), and past Editor-in-Chief of Human Reproduction Update. He previously held posts as a Fulbright scholar at the University of California, San Diego; and visiting professorships at Stanford University School of Medicine (California, USA), Free University of Brussels (Belgium), University of Siena (Italy), University of Southampton (UK), and the University of Adelaide (Australia). His major research interests include the pathophysiology of human ovarian function (especially PCOS, POI, and ovarian aging), ovarian stimulation, IVF and women’s health (healthy female aging). Professor Fauser published over 500 peer-reviewed scientific articles, Hirsch factor 119 (SCOPUS), and he is the No 3 in the 2025 Global Stanford/ Elsevier Top Scientist list in the field of Obstetrics and Gynecology. He acted as the editor of multiple textbooks, wrote chapters for all leading textbooks in Reproductive Medicine, lectured all around the world and his work has been widely covered in the national and international news media.
John Aitken is a reproductive biologist who, for the past 25 years, has been working at the University of Newcastle, NSW, initially, as Chair of Biological Sciences and, subsequently, as Director of the ARC Centre of Excellence in Biotechnology & Development and Pro Vice Chancellor of the Faculty of Health and Medicine. He is currently Distinguished Emeritus Laureate Professor of Biological Sciences and Scientific Advisor to a biotechnology company, Memphasys.
Adam Balen is an NHS consultant at Leeds Teaching Hospitals NHS Trust, UK, with a personal Chair in Reproductive Medicine and Surgery. He is clinical lead of a large multidisciplinary reproductive medicine service, including paediatric & adolescent gynaecology. He has been interested in PCOS for many years and has been a member of the international consensus groups on its definition and management including the Global PCOS Guideline Group, published in 2018 and 2023. He is a member of the WHO Guideline Development Group on Infertility (since 2012) and was responsible for formulating the FIGO definition of disorders of ovulation (2022). [ Full Article ]
News: Cancer after fertility treatment: reassuring on the whole, nuanced in the details
IVF.net Newsdesk 16 March 2026
One of the more persistent questions around IVF and related fertility treatments is whether hormonal stimulation and repeated treatment exposure might translate into a higher long term cancer burden. A new population based analysis in JAMA Network Open offers a reassuring answer at the broadest level: among 417,984 Australian women who underwent medically assisted reproduction between 1991 and 2018, overall cancer incidence was not higher than in age matched, calendar year matched, and jurisdiction matched women in the general population. The cohort included women exposed to ART, intrauterine insemination with ovarian stimulation, and clomiphene citrate, with cancer outcomes followed for an average of about 10 years. That headline matters. It helps move the discussion away from a vague fear that “fertility treatment causes cancer” and toward a more precise reading of the evidence. This was not a trial of treatment toxicity. It was a descriptive epidemiologic study comparing observed cancer incidence patterns in women who had used medically assisted reproduction with those in the general population. The authors are explicit that causation cannot be inferred from these data, and that the results should be used to guide awareness and follow up rather than to assign direct treatment related risk. Where the paper becomes more interesting is in the granularity. Although total cancer incidence was unchanged, some individual cancers were modestly more common. The study identified higher incidence for uterine cancer, ovarian cancer, and cutaneous melanoma, while cervical cancer and cancers of the trachea, bronchus, and lung were less common than expected. FemTech World’s summary usefully translates the relative effects into a clinically calmer frame: even where relative increases were seen, the largest excess translated to only a few additional cases per 100,000 women per year. In other words, the signal is real enough to examine, but still small in absolute terms. For reproductive scientists, the most important interpretive point is that these differences likely reflect population composition as much as, or more than, treatment exposure itself. Women who seek fertility care are not a random sample of the general population. Underlying infertility diagnoses matter. Endometriosis and polycystic ovary syndrome, for example, are already linked to uterine and ovarian cancer risk. Screening behavior matters too. Fertility patients often enter treatment only after up to date cervical screening and broader medical review, which could plausibly contribute to lower cervical cancer incidence. Lifestyle and phenotype may also play a role. The paper notes that smoking, skin type, adiposity, breastfeeding history, and treatment indication were not available at person level, and these are exactly the kinds of variables that can shape the apparent cancer profile of a treated population. The melanoma finding is a good example of why mechanistic caution is warranted. An elevated melanoma incidence may initially invite speculation about hormonal pathways, but the authors point to more ordinary explanations such as selection and detection effects. In Australia, medically assisted reproduction users may be more likely to be fair skinned and to have greater healthcare access, both of which could inflate melanoma detection relative to the general population. That does not make the association unimportant. It simply means the association is not self interpreting. The breast cancer results are similarly reassuring, though they require careful wording. The study did not find an increase in invasive breast cancer overall. A noninvasive breast cancer signal was seen in some IVF exposed women, but the balance of evidence in the paper does not support special population level breast screening recommendations solely because a woman has undergone medically assisted reproduction. That is an important distinction for clinicians and patients alike. Heightened vigilance is reasonable. A narrative of broad alarm is not. Methodologically, the study is impressive in scale and in its use of linked administrative and registry data across Australia. At the same time, its limitations are exactly the ones an experienced reader would expect. The comparator was the general population, not an infertility matched untreated group. Follow up remains relatively short for some malignancies, and many women were still younger than 50 years at the end of follow up. Treatment trajectories were heterogeneous, and the analysis was designed to describe population burden rather than individual level risk. These are not fatal weaknesses, but they do define the boundaries of what can and cannot be concluded. So where does this leave the field? In a better place, I think. The study supports a message of reassurance without flattening the biology or the epidemiology. Fertility treatment, including IVF, does not appear to be associated with a higher overall cancer incidence at the population level in this large cohort. At the same time, some site specific differences exist and deserve continued study, especially as treated populations age and follow up lengthens. For scientists and clinicians, the most responsible interpretation is neither complacency nor fear. It is disciplined nuance: routine screening should continue, underlying infertility diagnoses should remain central to counseling, and future work should aim for better phenotype adjustment and more informative comparison groups.
Sources 11 March 2026. The Conversation. 10 March 2026. Medscape 10 March 2026. JAMA Network 12 March 2026. Femtech World [ Full Article ]
News: ART & Embryology training program
Chennai Fertility Centre and Research Institute 06 March 2026
Training Batch Schedule April 2026 Batch - IV : 06th to 21st April 2026The International School of Embryology a unit of Chennai Fertility Centre and Research Institute was established to offer training in Advanced Reproductive Techniques and Embryology for clinicians and embryologists. It will help them to know in-depth knowledge and have good hands-on training. The members of our teaching faculty aim to bring Clinician and Embryologists to the highest level of knowledge about Assisted Reproductive Technology and practical capability. Our courses cover basics in Andrology, Embryology, ICSI & Cryosciences (Hands-on). Limited Seats. For admission Contact 9003111598 / 8428278218 [ Full Article ]
News: 22nd Royan International Congress on Stem Cell Biology & Technology
Royan Institute 25 February 2026
The 27th Royan International Reproductive Medicine Congress and the 22nd Royan International Stem Cell Technology Congress will be organized by Royan Institute, affiliated with ACECR, in Tehran, Iran, from September 2 to 4, 2026. These congresses will be held at Shahid Beheshti University, Abū Rayḥān Hall. Over the past years, twenty-six editions of this prestigious international scientific event have been successfully organized, playing a significant role in fostering collaborative scientific research and attracting prominent scientists and researchers from around the world. According to the Public Relations Office of Royan Institute, the congress will include two international events conducted in English, focusing on Reproductive Biomedicine and Stem Cell Technology. In addition, a specialized seminar in Persian on Nursing and Midwifery will be held concurrently. Detailed information regarding the scientific topics of the congress is available to researchers through the official congress website at www.royancongress.com. The Scientific Secretary of the 27th International Reproductive Medicine Congress is Dr. Azam Dalman. The Scientific Secretary of the 22nd International Stem Cell Technology Congress is Dr. Reza Moghadasali. The Scientific Secretary of the Nursing and Midwifery Seminar is Naimeh Sadat Mirghavam, and the Executive Secretary of the Congress is Dr. Ruhollah Fathi. Researchers interested in participating in this international scientific event are invited to submit their abstracts through the Royan Congress website by April 20, 2026. The final evaluation results of the submitted abstracts will be announced on July 5, 2026. This congress provides a valuable platform for domestic and international researchers to present their latest scientific achievements, exchange knowledge, and establish collaborative research partnerships. Dr. Shahzadeh Fazeli, Deputy for Research and Technology at Royan Institute, stated that alongside the 27th Royan International Twin Congress, the Kazemi Prize will also be held. This award aims to promote scientific excellence and strengthen scientific communication among national and international researchers. The Kazemi Prize commemorates a distinguished scientist who dedicated his life to advancing human health and alleviating suffering through scientific innovation. For further information, please contact: [ Full Article ]
News: 27th Royan International Congress on Reproductive Medicine
Royan Institute 25 February 2026
The 27th Royan International Reproductive Medicine Congress and the 22nd Royan International Stem Cell Technology Congress will be organized by Royan Institute, affiliated with ACECR, in Tehran, Iran, from September 2 to 4, 2026. These congresses will be held at Shahid Beheshti University, Abū Rayḥān Hall. Over the past years, twenty-six editions of this prestigious international scientific event have been successfully organized, playing a significant role in fostering collaborative scientific research and attracting prominent scientists and researchers from around the world. According to the Public Relations Office of Royan Institute, the congress will include two international events conducted in English, focusing on Reproductive Biomedicine and Stem Cell Technology. In addition, a specialized seminar in Persian on Nursing and Midwifery will be held concurrently. Detailed information regarding the scientific topics of the congress is available to researchers through the official congress website at www.royancongress.com. The Scientific Secretary of the 27th International Reproductive Medicine Congress is Dr. Azam Dalman. The Scientific Secretary of the 22nd International Stem Cell Technology Congress is Dr. Reza Moghadasali. The Scientific Secretary of the Nursing and Midwifery Seminar is Naimeh Sadat Mirghavam, and the Executive Secretary of the Congress is Dr. Ruhollah Fathi. Researchers interested in participating in this international scientific event are invited to submit their abstracts through the Royan Congress website by April 20, 2026. The final evaluation results of the submitted abstracts will be announced on July 5, 2026. This congress provides a valuable platform for domestic and international researchers to present their latest scientific achievements, exchange knowledge, and establish collaborative research partnerships. Dr. Shahzadeh Fazeli, Deputy for Research and Technology at Royan Institute, stated that alongside the 27th Royan International Twin Congress, the Kazemi Prize will also be held. This award aims to promote scientific excellence and strengthen scientific communication among national and international researchers. The Kazemi Prize commemorates a distinguished scientist who dedicated his life to advancing human health and alleviating suffering through scientific innovation. For further information, please contact: [ Full Article ]
Webinar: All’s Well That Endos Well
International IVF Initiative 21 February 2026
All’s Well That Endos Well
3rd March, 3pm EST, 8pm UK, 9pm CET Moderator: Dr. Dan Nayot & Dr. Sony Sierra
Dr. Jose María Puerta Sanabria: Decoding Endometriosis: Precision Diagnostics, Surgical Breakthroughs Dr. Demian Glujovsky: Endometrial receptivity–guided embryo transfer: a systematic review and meta-analysis of the evidence Q and A [ Full Article ]
News: PG Diploma in Clinical Embryology and Preimplantation Genetics Course
Chennai Fertility Centre and Research Institute 02 February 2026
Training Batch Schedule March 2026 Batch - III : 09th to 23th MarchThe International School of Embryology a unit of Chennai Fertility Centre and Research Institute was established to offer training in Advanced Reproductive Techniques and Embryology for clinicians and embryologists. It will help them to know in-depth knowledge and have good hands-on training. The members of our teaching faculty aim to bring Clinician and Embryologists to the highest level of knowledge about Assisted Reproductive Technology and practical capability. Our courses cover basics in Andrology, Embryology, ICSI & Cryosciences (Hands-on). Limited Seats. For admission Contact 9003111598 / 8428278218 [ Full Article ]
News: Natural-cycle endometrial preparation for frozen embryo transfer holds up, and may be safer
IVF.net Newsdesk 26 January 2026
Frozen embryo transfer now sits at the center of modern IVF, shaped by freeze-all strategies, single embryo transfer, and the growth of PGT cycles. As FET volumes have climbed, so has a practical and clinical question that many programs have learned to live with rather than resolve: should we prepare the endometrium by tracking a patient’s own ovulation, or by suppressing and replacing the cycle with exogenous estrogen and progesterone? A new multicentre randomized clinical trial provides unusually strong footing for that decision. In ovulatory women planning frozen single blastocyst transfer, a natural ovulation regimen achieved healthy live birth rates that were statistically indistinguishable from a programmed hormone replacement regimen, while showing lower rates of several important maternal complications. Study design in brief, with the details that matter clinically The trial enrolled 4,376 ovulatory women aged 20–40 years across 24 academic fertility centres in China. Participants were randomized 1:1 to either a natural ovulation regimen or a programmed regimen for endometrial preparation. The natural arm relied on ultrasound monitoring of follicular development plus serial serum hormone measurements (luteinising hormone, oestradiol, progesterone) to time transfer, with a modified natural approach (hCG trigger) permitted when appropriate. The programmed arm used sequential exogenous oestrogen and progesterone to prepare the lining on a set schedule. Importantly, this was not a small, single-center comparison powered only for pregnancy rates. The investigators prespecified dual primary outcomes: healthy live birth and pre-eclampsia or eclampsia following FET, with a broad set of secondary outcomes spanning cancellation, pregnancy milestones, pregnancy loss, and maternal, fetal, and neonatal complications. Efficacy: similar healthy live birth rates in intention-to-treat analysis The headline efficacy result is straightforward. In intention-to-treat analyses, 41.6% (910/2185) of patients in the natural ovulation arm achieved a healthy live birth, compared with 40.6% (890/2191) in the programmed arm (relative ratio 1.03; 95% CI 0.96 to 1.10; P=0.49). In other words, within the precision of this dataset, natural-cycle preparation performed as well as programmed hormone replacement in achieving the outcome patients care about most. Safety: a consistent signal toward fewer maternal complications with natural ovulation Where the trial becomes especially practice-shaping is maternal safety. Among patients who achieved clinical pregnancy, the risk of pre-eclampsia was lower in the natural ovulation arm: 2.9% (38/1302) versus 4.6% (61/1326), with a relative ratio of 0.63 (95% CI 0.43 to 0.94; P=0.02). No eclampsia was observed in either group. Several other obstetric outcomes also favored the natural ovulation approach. The natural arm showed lower incidences of early pregnancy loss (12.1% vs 15.2%), placental accreta spectrum (1.8% vs 3.6%), caesarean section (69.5% vs 75.6%), and postpartum haemorrhage (2.0% vs 6.1%). Neonatal outcomes, at least as captured here, did not differ meaningfully between groups. Birth weight and neonatal complication rates were similar, which is reassuring given the current reality that many programs default to programmed cycles for convenience and scheduling. The trade-off: higher cancellation in the natural ovulation arm Natural-cycle FET is rarely rejected because of concerns about implantation biology. More commonly, it is rejected because of operational fragility. The trial reflects that reality. Cycle cancellation was higher with natural ovulation: 16.2% (354/2185) versus 11.5% (251/2191), with cancellations in the natural arm mainly driven by absent or arrested follicle development. This is the part that tends to shape lab and clinic sentiment. A higher cancellation rate means more monitoring, more uncertainty in thaw scheduling, and a greater chance of wasted preparation time for both patient and team. The key contribution of this trial is that it puts that inconvenience into a clearer risk-benefit frame: the convenience of a programmed regimen comes with a measurable increase in several maternal complications in this ovulatory population, even though the chance of a healthy live birth is similar. Why might the presence of ovulation matter for maternal outcomes? The trial itself is clinical rather than mechanistic, but it lands neatly on a biological hypothesis that has been building for years: the corpus luteum is not just a progesterone factory, and replacing progesterone does not necessarily replace luteal physiology. In a programmed regimen, the endometrium can be rendered receptive, but the cycle may proceed without a functional corpus luteum. Observational work has linked programmed cycles to higher rates of hypertensive disorders of pregnancy, including pre-eclampsia, raising the possibility that vasoactive substances produced by the corpus luteum contribute to maternal vascular adaptation and placentation. That hypothesis does not require a claim that programmed cycles are unsafe in all contexts. It suggests something narrower and more actionable: for people who can ovulate reliably, preserving ovulation and the luteal endocrine milieu may reduce downstream maternal risk, even when the embryo is thawed and transferred in a highly controlled lab environment. How this shifts protocol conversations in real clinics New Scientist framed the finding in the way many clinicians will instinctively interpret it: if outcomes are equivalent and maternal risks are lower, natural ovulation looks like the better default for ovulatory patients undergoing FET. BMJ’s own summary makes the same point while emphasizing the maternal complication profile. In practice, “default” rarely means “only.” Programmed regimens remain essential for several common scenarios: irregular cycles, ovulatory dysfunction, donor or surrogate arrangements where scheduling constraints are significant, and situations where clinic operations make intensive monitoring impractical. The clinical value of this trial is that it strengthens the case for offering natural or modified natural approaches more proactively in people who are good candidates, rather than treating them as a boutique option for patients willing to accept more monitoring. For lab teams, the implications are familiar but worth stating plainly. Natural and modified natural protocols push scheduling variability upstream into monitoring and trigger decisions, and downstream into thaw and transfer timing. That variability is manageable, but it benefits from strong internal coordination: clear cutoffs for LH surge interpretation, standardized trigger criteria when using hCG, and robust communication paths between clinic and lab so that warming plans track real-time endocrine and ultrasound findings. For counselling, the framing becomes cleaner. Patients can be told that, in a large randomized dataset of ovulatory women undergoing frozen transfer, natural-cycle preparation achieved similar healthy live birth rates while lowering the risk of several maternal complications, at the cost of a higher chance that the cycle will be cancelled and need to be restarted. Where this leaves the field FET protocols have always been a blend of biology and logistics. The biology has been debated, but the logistics often decided the matter. This trial does not eliminate the logistical advantages of programmed cycles, and it does not claim that every patient should shift protocols. What it does is raise the evidentiary bar for treating convenience as neutral. If you work in a setting where programmed cycles have become the unexamined norm for ovulatory patients, this is the kind of paper that justifies revisiting that norm, not because the old approach “fails,” but because equivalent efficacy combined with lower maternal complication rates is a rare and valuable combination in reproductive medicine. Sources 23 January 2026. New Scientist 21 January 2026. British Medical Journal 22 January 2026. BMJ Group [ Full Article ]
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