Monthly IVF research brief for April 2025

Here you’ll find a brief summary of new IVF studies for April* that I think are helpful for patients. I’ll be updating this post each week of April with new studies, before making a separate post for next month.

*Note that the publication dates of these studies might be outside of the indicated period, mostly because of how PubMed indexes the article and when I put this list together.

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Week 1 (Apr 1 – Apr 7)

Risk factors for recurrent implantation failure as defined by the European Society for Human Reproduction and Embryology. A study investigated unrecognized risk factors for recurrent implantation failure, finding that AMH emerged as the strongest predictor, with chronic endometritis, intrauterine adhesions, and BMI also identified as significant risk factors. This suggests that these elements should be considered in managing RIF alongside traditional factors like age.

Lower pregnancy rate in women with high uterine peristalsis before embryo transfer: a systematic review and meta-analysis. A meta-analysis combined the results of 17 studies and found that high uterine contractility at the time of embryo transfer significantly reduced pregnancy rates, underscoring the need to consider uterine peristalsis as a factor in fertility treatments.

Expert-based recommendations for human witnessing in assisted reproductive technology: an Italian perspective. A survey conducted among members of the Italian Society of Embryology revealed that the most effective human witnessing strategies in IVF labs include verbal confirmations, standardized documentation, and specialized training for healthcare professionals, with an emphasis on structuring shifts to maintain attentiveness and reduce errors.

Reduced live birth rates following ART in adenomyosis patients: a matched control study. In a study, women with adenomyosis showed significantly lower cumulative live birth rates compared to matched controls after IVF, confirming adenomyosis as an independent risk factor for reduced ART success.

Late maturing oocyte rescue in poor-prognosis patients: delayed intracytoplasmic sperm injection results in more viable embryos. A study found that rescue in vitro maturation (IVM) can yield fertilization and live birth rates comparable to standard procedures, with nearly 10% of IVF cycles in poor prognosis leading to live births that wouldn’t have otherwise.

Association between hatching status and pregnancy outcomes in single blastocyst transfers: a retrospective cohort analysis. A study found that late-hatching blastocysts, compared to earlier hatching stages, are significantly associated with higher clinical pregnancy and live birth rates following single blastocyst transfer.

Patient perspectives after receiving simulated preconception polygenic risk scores (PRS) for family planning. A study investigating patient perspectives on using PGT-P revealed high support for screening embryos for childhood-onset diseases and specific adult-onset cognitive disorders.

Week 2 (Apr 8 – Apr 14)

Early embryo development: What does daddy do? This review provides an overview of how sperm contribute to embryo development, through a variety of RNAs, including mRNAs, small RNAs, and non-coding RNAs.

Late bloomers: exploring the reproductive potential of day 7 embryos. This review evaluates the potential of day 7 embryos, which are less commonly used due to lower blastulation and higher aneuploidy rates compared to day 5 and 6 embryos, but still show significant pregnancy and live birth rates.

Blastocyst re-expansion rate immediately after warming is a strong dynamic indicator of embryo quality. This study found that frozen blastocysts that re-expand 9-11 minutes after thawing had a higher chance of pregnancy.

Effect of myo-inositol supplementation in mixed ovarian response IVF cohort: a systematic review and meta-analysis. This meta-analysis combined the results of 11 studies on myo-inositol supplementation, finding that it significantly improves the egg maturation and fertilization rates, particularly for women with PCOS. They didn’t find any benefit for poor responders.

Adoptive transfer of regulatory T cells inhibits the progression of endometriosis-like lesions in regulatory T-cell-depleted mice. This study investigated whether restoring regulatory T cells (Tregs) can suppress endometriosis progression. It found that adoptive transfer of Tregs in mice not only curbed the growth of endometriosis-like lesions but also significantly reduced the levels of Th-cell-related and pro-inflammatory cytokines, suggesting a potential therapeutic approach for managing endometriosis by modulating immune response.

School-age outcomes among IVF and ICSI-conceived children: a causal inference analysis using linked population-wide data. This study examined the long-term effects of ICSI compared to standard IVF on early childhood development, finding no significant difference in developmental vulnerability at school entry between children conceived via ICSI and those via standard IVF.

IVF versus ICSI in patients without severe male factor infertility: a randomized clinical trial. A multicenter randomized controlled trial compared the cumulative live birth rates (CLBR) of ICSI and conventional in vitro fertilization (c-IVF) in patients without severe male factor infertility. The results showed that ICSI did not improve CLBR compared to c-IVF, suggesting c-IVF should be the preferred first-line treatment for these patients.

Week 3 (Apr 15 – Apr 21)

Efficacy of hormone pre-treatment before ART to improve reproductive outcomes in infertile women with endometriosis: Network meta-analysis of randomized controlled trials. A meta-analysis combined the results of 9 studies investigating endometriosis treatment on IVF outcomes with GnRH agonists for 1 or 3 months (like leuprorelin/lupron depot) or administration of progestins. They found no advantage in using these treatments to improve clinical pregnancy and live birth rates, while some protocols showed improvements in implantation rates.

The impact of PGT-A on time to live birth in IVF. This study found that PGT-A shortened the time to live birth and improved outcomes in women aged 38 and older, but provided no significant benefit for younger women undergoing IVF.

Could blastocysts derived from abnormal fertilized zygotes be used? A systematic review and meta-analysis. This meta-analysis combined the results of 16 studies that investigated the use of abnormally fertilized zygotes (1PN and 0PN). They found that 1PN and 0PN blastocysts had lower clinical pregnancy and live birth rates compared to normally fertilized 2PN blastocysts.

The Role of Cumulus Cells for The Immature Oocyte Undergoing In Vitro Maturation Rescue: A Retrospective Analysis. This study found that immature eggs that had rescue IVM showed improved fertilization and cleavage rates if their cumulus cells weren’t removed.

Analysis of mitochondrial DNA quantification in human blastocysts and assisted reproduction outcomes. This study found that mitochondrial DNA levels (measured through PGT-A) had no impact on predicting pregnancy outcomes.

Assisted sperm fusion insemination improves fertilization rates and increases usable embryos for transfer: a clinical sibling-oocyte study. This study describes a new form of ICSI called assisted sperm fusion insemination that showed increased fertilization rates and lower rates of degeneration. It involves inserting the needle with the sperm in through the zona and placing the sperm directly on top of the egg without actually piercing the egg itself, and might be promising for patients with more fragile eggs.

Considerations on optimizing the patient experience during assisted reproductive technology treatment: a qualitative analysis. This study identified key factors affecting the ART patient experience, finding that financial stress, poor provider communication, and managing injections were major challenges, while supportive relationships, shared decision-making, and complementary therapies like acupuncture improved the experience.

Examining the fate of frozen embryo inventory: an analysis of patients’ embryo disposition decisions. This study evaluated the disposition of frozen embryos, finding that most patients chose to discard their frozen embryos rather than donate them to research, with donors more likely to have experienced recurrent pregnancy loss, transferred more embryos (especially euploid), and achieved a live birth.

Week 4 (Apr 22 – Apr 28)

Morphological parameters of the blastocyst to predict embryo quality: a systematic review and meta-analysis. A meta-analysis combined the results of 33 studies that ranked the importance of embryo expansion, trophectoderm grade and inner cell mass grade. They found that the trophectoderm grade was most influential in predicting live birth, followed by the ICM grade and expansion.

“Thin endometrium” at single-cell resolution. This publication reviews the causes of thin endometrium (less than 7 mm), highlighting that it is often linked to a history of uterine trauma (such as a D&C), which can trigger an “accelerated aging process” that results in a thin endometrium with impaired and dysfunctional immune cells.

Optimal timing to transfer embryos for women who underwent hysteroscopy: a systematic review and meta-analysis. This meta-analysis combined the results of 5 studes to investigate the optimal time interval between hysteroscopy and embryo transfer, finding that embryo transfer within 120 days (especially within 50 days if no major problems were found) leads to better pregnancy and live birth rates.

Analysis of Surplus Cryopreserved Blastocysts in Fresh Donor Oocyte Cycles. This study found that fertilizing 15 to 20 donor eggs (instead of a higher number) balances a good chance of live birth while avoiding creating too many extra embryos.

Physical activity, sedentary time, and sperm DNA fragmentation index in healthy Japanese men. This study found that in healthy Japanese men, being more physically active and spending less time sitting were linked to lower DNA fragmentation, but they didn’t see major changes in regular semen measures like sperm count or motility.

An interpretable artificial intelligence approach to differentiate between blastocysts with similar or same morphological grades. This study developed a deep learning tool called BlastScoringNet that gives embryos a more precise score (rather than just a letter grade), helping embryologists better tell which embryos — even those with similar grades — have the best chance of leading to a live birth.

CCR8+ decidual regulatory T cells maintain maternal-fetal immune tolerance during early pregnancy. This mouse study found that a special type of immune cell (CCR8+ T regulatory cells) helps protect pregnancies by supporting immune tolerance in the uterus, and that a shortage of these cells may contribute to recurrent pregnancy loss.

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About Embryoman

Embryoman (Sean Lauber) is a former embryologist and the founder of Remembryo, an IVF research and fertility education website. After working in an IVF lab in the US, he returned to Canada and now focuses on making fertility research more accessible. He holds a Master’s in Immunology and launched Remembryo in 2018 to help patients and professionals make sense of IVF research. Sean shares weekly study updates on Facebook, Instagram, and Reddit regularly. He also answers questions on Reddit or in his private Facebook group.

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