Monthly IVF research brief for May 2025

Here you’ll find a brief summary of new IVF studies for May* that I think are helpful for patients. I’ll be updating this post each week of May 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.

---

Week 1 (Apr 29 – May 5)

The Istanbul consensus update: a revised ESHRE/ALPHA consensus on oocyte and embryo static and dynamic morphological assessment. ESHRE/Alpha Scientists in Reproductive Medicine have produced a new Istanbul consensus on recommendations for how embryologists should assess and rank eggs and embryos based on features like the egg’s shape, color, and granularity; the number of pronuclei after fertilization; and how embryos should be assessed at different stages — including things like cell number, inner cell mass structure, and how quickly the embryo collapses or expands.

Upregulation of immune genes in the proliferative phase endometrium enables classification into women with recurrent pregnancy loss versus controls. This study found that women with recurrent pregnancy loss have a distinct gene expression pattern in their endometrium even before conception, especially involving immune-related genes, which may help identify those at higher risk for future losses.

The number of autologous, vitrified mature oocytes needed to obtain three euploid blastocysts increases with age. This study found that to produce at least 3 euploids, women under 35 needed about 15 mature eggs, while women over 40 needed three times as many.

Increasing Endometrial Thickness up to 12mm Is Associated with Increased Odds of Live Birth Among Fresh and Frozen-Thawed Autologous Transfers with or without PGT. This large study found that live birth rates increased as endometrial thickness rose from 5 mm to around 12 mm, with the best outcomes seen between 8–12 mm.

The phenotypic and genetic association between endometriosis and immunological diseases. This study found that women with endometriosis have a higher risk of developing immune-related diseases, like rheumatoid arthritis, partly due to shared genetic factors, suggesting a biological link that could help guide future treatments and early screening.

Global Andrology Forum Clinical Guidelines on the Relevance of Sperm DNA Fragmentation in Reproductive Medicine. Experts from the Global Andrology Forum outline when and how sperm DNA fragmentation testing may be useful in fertility care.

A compound heterozygous mutation in ZP1 and two novel heterozygous cis mutations in ZP3 causes infertility in women presenting with empty follicle syndrome. This study found that rare genetic mutations in the ZP1 and ZP3 genes may cause empty follicle syndrome, a condition where no eggs are retrieved during IVF despite normal follicle development. This highlights the role of genetics in some cases of unexplained female infertility and supporting the use of genetic testing and egg donation as next steps.

Reassessing the conventional fertilization check: leveraging preimplantation genetic testing for aneuploidy to increase the number of transferrable embryos. This study found that some embryos from abnormally fertilized eggs can still be chromosomally normal and lead to healthy pregnancies, suggesting that these embryos shouldn’t automatically be discarded and may be worth testing with PGT-A.

Week 2 (May 6 – May 12)

Chaotic blastocysts in preimplantation genetic testing for aneuploidy: prevalence, characterization, and re-biopsy results. This study investigated whether embryos labeled as “chaotic” by PGT-A could actually be viable by performing re-biopsies and re-analysis on 93 donated blastocysts. While most chaotic embryos remained abnormal upon retesting, over half of those classified as mosaic chaotic were reclassified as euploid.

Effects of Various Transfer Strategies of Frozen-Thawed Cleavage-Stage and Blastocyst Embryos on Pregnancy and Neonatal Outcomes in Different Age Groups. This study compared pregnancy and birth outcomes from different FET strategies based on embryo stage, quality, and number, in women younger and older than 35. Transferring two high-quality cleavage embryos improved success rates across all ages, but for blastocyst transfers, younger women benefited from single transfers to reduce risks of multiple pregnancy, while older women saw better outcomes with double blastocyst transfers.

The transfer of double morphologically good Day 5 blastocysts increases the risk of clinical pregnancy loss in singleton pregnancies following frozen-thawed embryo transfer. This study looked at whether transferring two embryos instead of one raises the risk of miscarriage in pregnancies where only one baby develops. It found that when two top-quality blastocysts were transferred, the chance of miscarriage was higher, likely because the loss of the second embryo may cause intrauterine inflammation that compromises the surviving embryo. This suggests that one embryo could influence the implantation of the other embryo in a double embryo transfer.

The genetics of preimplantation embryonic arrest: the role of aneuploidies. This review explores how chromosome errors, especially those that happen after fertilization during early cell divisions, contribute to embryo arrest in IVF.

The Effect of Chewing Gum in Managing Labor Pain Intensity and Anxiety Level in Primiparous Women: A Randomized Controlled Trial. This randomized controlled study tested whether chewing gum could help reduce pain and anxiety during labor in first-time mothers. Women who chewed gum during different stages of labor had significantly lower pain and anxiety levels compared to those who received standard care, suggesting it may be a simple, non-medicated option to support natural childbirth.

From hope to hesitation: why couples fail to return for infertility treatment after the first consultation. This study explored why some couples do not return for fertility treatment after their first consultation, analyzing over 28,000 cases. Older age, low ovarian reserve, and eligibility for donor gametes were key reasons, along with factors like spontaneous pregnancy, transferring care, or emotional distress.

Week 3 (May 13 – May 19)

Effects of emotions on IVF/ICSI outcomes in infertile women: a systematic review and meta-analysis. This meta-analysis of 29 studies examined whether mental health affects IVF and ICSI success, focusing on depression, anxiety, and stress in infertile women. It found that higher levels of anxiety and depression were linked to lower pregnancy rates, highlighting the importance of psychological support during fertility treatment.

Effects of acupuncture-related therapies on pregnancy outcomes among women undergoing in vitro fertilization and embryo transfer: a Bayesian network meta-analysis. This network meta-analysis reviewed 96 randomized trials to evaluate how different acupuncture-based therapies affect pregnancy outcomes in IVF. Treatments like warm acupuncture or acupuncture combined with moxibustion for several cycles before egg retrieval showed the greatest improvements in clinical pregnancy rates, while brief acupuncture around embryo transfer had limited benefit.

The role of granulocyte-macrophage colony-stimulating factor in female assisted reproductive technology treatment: a systematic review and meta-analysis. This meta-analysis combined studies involving the use of GM-CSF in assisted reproductive technology, finding that while randomized trials showed no clear benefit, data from non-randomized studies suggested that GM-CSF may boost implantation, clinical pregnancy, live birth, and embryo quality in some patients.

Comparative efficacy of intrauterine infusion treatments for recurrent implantation failure: a network meta-analysis of randomized controlled trials. This network meta-analysis compared intrauterine infusion treatments for women with recurrent implantation failure undergoing IVF, including G-CSF, PRP, hCG and PBMCs. Among 25 randomized trials, PRP and PBMCs were the most effective at improving pregnancy and live birth rates, with PRP ranking highest overall.

The Fate of Zona free Oocyte Following Intracytoplasmic Sperm Injection: A Case Report and Review of Literature. This case report describes the development of a zona-free oocyte after accidental detachment of the zona pellucida during egg preparation in a 44-year-old patient. Although the oocyte fertilized and developed into a four-cell embryo, it failed to implant.

Week 4 (May 20 – May 26)

A systematic review and meta-analysis of the diagnostic accuracy after preimplantation genetic testing for aneuploidy. This meta-analysis assessed how often embryos are misdiagnosed as aneuploid or euploid after PGT-A. Based on pregnancy data, fewer than 1% of euploid embryos were misdiagnosed, while about 1 in 5 mosaic embryo pregnancies were later found to be euploid, indicating a higher misdiagnosis rate for mosaics.

Mosaicism is more than meets the eye: transcriptional consequences of blastocyst mosaicism. This study examined how mosaicism affects gene expression in embryos by analyzing both DNA and RNA from 76 blastocysts. Mosaic embryos showed distinct transcriptional profiles, especially in genes linked to implantation and cell function, suggesting that their mixed chromosome makeup may reduce implantation potential, though some still retain the ability to develop.

FSH receptor N680S genotype-guided gonadotropin choice increases cumulative pregnancy and live birth rates after in vitro fertilization. This study found that tailoring ovarian stimulation based on a woman’s FSH receptor (FSHR) genotype can improve IVF outcomes. Women who received the FSH type best suited to their genetic variant, urinary FSH for women with one type of FSHR and recombinant FSH for another type, had significantly higher pregnancy and live birth rates than those treated without genetic guidance.

Receptive window might be shorter in patients with endometriosis and lesions cyclically prepare for implantation. This study investigated whether endometrial receptivity is altered in women with endometriosis by examining podocalyxin (PCX), a protein that helps regulate embryo implantation. It found that women with endometriosis may have a shorter window of receptivity and that PCX loss in endometriotic lesions could increase their ability to stick to nearby tissues, potentially worsening the condition.

Association between exposure to volatile organic compounds and female infertility: An NHANES analysis. This study analyzed data from US women and found that higher levels of certain chemical byproducts (VOCs) in urine were linked to a greater chance of infertility. While the study doesn’t prove these chemicals cause infertility, it suggests environmental exposures may play a role in reproductive health.

Long COVID and endometriosis: a systematic review and meta-analysis. This review found that women with endometriosis may be more likely to experience long COVID, based on data from two large observational studies. While the association was statistically significant, more research is needed to confirm the link and understand why women with endometriosis could be at greater risk.

Week 5 (May 27 – June 2)

Advanced maternal age was associated with an annual decline in reproductive success despite use of donor oocytes: A retrospective study. This large study of over 33,000 donor egg IVF cycles found that reproductive outcomes begin to decline around age 40, even when high-quality embryos from young donors were used. This suggests that the uterus itself, not just the egg or embryo, may contribute to age-related declines in IVF success.

First follicular fluid cf-mtDNA sequencing unveils ovarian stimulation-induced mutations impacting oocyte quality and IVF success. This study sequenced mitochondrial DNA in follicular fluid for the first time and found that ovarian stimulation can cause mtDNA mutations, especially with longer treatment durations. These mutations were linked to fewer eggs, lower embryo quality, and reduced IVF success, suggesting they could serve as markers to guide and improve stimulation protocols.

Intravenous immunoglobulin versus placebo in recurrent pregnancy loss: A systematic review and meta-analysis of randomized trials. This meta-analysis reviewed data from 10 trials to assess whether IVIg improves live birth rates in women with recurrent pregnancy loss (RPL). While IVIg did not significantly improve outcomes overall, it showed potential benefit in women with six or more prior losses.

Live Birth Rate Outcomes Following a Change in Endometrial Preparation After a Failed Frozen Embryo Transfer Cycle. This study evaluated whether changing the endometrial preparation protocol after a failed frozen embryo transfer (FET) improves the chance of live birth. It found no significant difference in live birth rates between women who changed protocols and those who didn’t.

Successful Clinical Outcome After a Modified Protocol of Rescue In Vitro Maturation of Oocytes: A Case Series Study. This case series reports five successful pregnancies using a rescue-IVM approach, where immature eggs collected after standard IVF retrieval were matured in the lab before fertilization.

If you want to get even more of the latest research each week, you can sign up for a paid subscription to Remembryo to get an upgraded weekly newsletter. Plus, you’ll be supporting me in my efforts to share the latest IVF research!

If you liked this post and want to support what I do, please consider a paid subscription, Patreon or donate through PayPal!

 

---

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.

---