u/embryomanofficial

Most children conceived through IVF appear to have similar long-term health to those conceived without fertility treatment.

Many people worry about whether IVF could affect their child's health later in life. To help answer that question, two large reviews by Le et al. (2026) and Firmin et al. (2026) summarized nearly 150 studies examining the long-term health of children conceived through IVF and ICSI.

Overall, the evidence found:

• Most birth defects and cardiovascular and metabolic outcomes were similar after IVF, although a few differences were reported.

• Brain development, growth, asthma, diabetes, and cancer were generally similar.

• Children conceived through ICSI had similar long-term health to those conceived through conventional IVF, with only some reported differences.

• PGT wasn't associated with differences in children's growth, blood pressure, or metabolic health, but longer-term data are still needed.

• Fresh and frozen embryo transfers differed in birth weight.

One important challenge is separating the effects of IVF itself from the effects of the parents' underlying infertility. Some of the reported differences may be related to infertility itself rather than the fertility treatment, but it's still not clear how much each contributes.

Overall, the evidence is reassuring. Importantly, most of the conditions studied were rare, affecting fewer than 1% of children. This means that even when an increased risk was found, the actual increase in the chance of developing the condition was very small.

✅ Check out more details on Remembryo: https://remembryo.com/do-children-conceived-through-ivf-have-long-term-health-problems/

✉️ Like this post? Get a free weekly summary of the latest IVF research: https://mailchi.mp/remembryo/x27kx5o1sw

The embryo is the biggest factor in whether implantation succeeds, but even after transferring a euploid embryo, many other factors can influence the chances of pregnancy.

Some of these include:

• Endometrial receptivity: The uterine lining must be ready to receive the embryo during a short window of implantation.

• The immune system: Implantation requires a carefully balanced immune response. In some patients, abnormal immune function may interfere with implantation.

• Endometriosis and adenomyosis: These conditions can alter the uterine environment through inflammation, hormone signaling, and changes in uterine function.

• Structural abnormalities: Fibroids, polyps, adhesions, hydrosalpinx, and uterine anomalies can reduce implantation by disrupting the uterine cavity or affecting endometrial function.

• Endometritis: Infection or chronic inflammation of the endometrium can reduce implantation and increase the risk of miscarriage.

• The microbiome: Changes in the bacteria living in the reproductive tract may also affect implantation, although the evidence is still evolving.

• Lifestyle and metabolic health: Smoking, obesity, insulin resistance, and other health factors may reduce the chances of a successful pregnancy.

• Clinical and lab factors: Embryo transfer technique and IVF laboratory performance can also influence outcomes.

Still, the exact reason a transfer failed often remains unknown. Implantation is one of the most complex processes in human reproduction, and researchers are still working to understand why some embryos implant while others don't.

✅ This post covers the basics. The full article on Remembryo goes into more detail: https://remembryo.com/why-do-embryos-in-ivf-fail-to-implant-or-miscarry/

✉️ Like this post? Sign up for my free Friday newsletter to stay updated on the latest IVF research: https://mailchi.mp/remembryo/x27kx5o1sw

After egg retrieval, some eggs are still immature and are often discarded.

Rescue in vitro maturation (IVM) is a technique where embryologists culture these immature eggs in the lab, often overnight, to give them time to mature before insemination.

In a new study, Cimadomo et al. (2026) performed rescue IVM on the most immature type of egg, called germinal vesicle (GV) oocytes.

Overall, 53.7% of GV eggs matured, but they were less likely to reach the blastocyst stage than eggs that were already mature when collected. However, blastocysts that did develop were just as likely to be euploid, and rescue IVM provided at least one additional euploid embryo in 11 of 47 patients. Overall, this contributed to a 20% relative increase in cumulative live birth rate.

This was a small retrospective study of patients with unexpectedly poor egg maturation. While larger studies are still needed, the results suggest that rescue IVM may provide another opportunity to obtain a transferable embryo instead of discarding these immature eggs.

✅ This post is a quick look at one study, rather than a full breakdown on Remembryo. Link to the study: https://academic.oup.com/humrep/advance-article/doi/10.1093/humrep/deag115/8733590?login=false

✉️ Like this post? Get a free weekly summary of the latest IVF research: https://mailchi.mp/remembryo/x27kx5o1sw

Researchers have looked at whether having sex before or after embryo transfer affects implantation or pregnancy rates, but the evidence is still mixed.

Many fertility clinics recommend avoiding sex around embryo transfer, with common reasons including concerns about uterine contractions after orgasm, a small risk of infection after embryo transfer, and (during natural frozen cycles) a small chance of a simultaneous spontaneous pregnancy.

A few studies have investigated if sex around embryo transfer affects success rates.

A new 2026 study of more than 1,300 women found no difference in pregnancy, live birth, or pregnancy loss rates between women who had sex during endometrial preparation and those who didn't.

Most earlier studies found similar results. However, one randomized trial found higher implantation and clinical pregnancy rates when couples had protected sex the night before frozen embryo transfer.

Researchers have suggested that sex might help implantation due to increased blood flow, hormonal changes, or improved immune signaling. One leading theory is that seminal plasma may help prepare the mother's immune system for pregnancy.

Interestingly, the only randomized trial to find a benefit involved protected sex, suggesting the explanation may be more complex than exposure to seminal plasma alone.

Overall, there isn't enough high-quality evidence to conclude that having sex around embryo transfer either improves or harms IVF outcomes.

✅ Check out more details on Remembryo: https://remembryo.com/does-sex-before-or-after-embryo-transfer-affect-implantation-or-pregnancy/

✉️ Like this post? Get a free weekly summary of the latest IVF research: https://mailchi.mp/remembryo/x27kx5o1sw

Researchers found that more than two-thirds of patients with complete embryo arrest still developed at least one usable blastocyst in their next IVF cycle.

Embryo arrest generally occurs when an embryo stops developing before reaching the blastocyst stage. However, IVF labs don't all use the same criteria for what they consider a usable blastocyst.

George et al. (2026) studied nearly 4000 patients who had two IVF cycles within one year to see if complete embryo arrest in the first cycle affected usable blastocyst formation in the next cycle. The study included PGT-A cycles, where only blastocysts that met the laboratory's biopsy and freezing criteria were counted (at least grade 4CC by day 7).

Patients with complete embryo arrest had lower usable blastocyst formation rates in their next cycle, and were more likely to experience complete embryo arrest again.

However, more than two-thirds of these patients still developed at least one usable blastocyst in their next cycle. Among the usable blastocysts that formed, the chances of being euploid and leading to a live birth after transferring a single euploid embryo were similar.

The researchers also found no evidence that changing the ovarian stimulation protocol or trigger medication improved usable blastocyst formation.

A limitation of this study is that they only counted usable blastocysts (at least grade 4CC by day 7), so the reported blastocyst formation rates excluded some blastocysts that didn't meet the lab's biopsy and freezing criteria.

✅ Check out more details on Remembryo: https://remembryo.com/what-to-expect-after-complete-embryo-arrest-during-ivf/

✉️ Like this post? Get a free weekly summary of the latest IVF research: https://mailchi.mp/remembryo/x27kx5o1sw

Mosaic embryos are generally classified in two major ways:

1. How much of the biopsy contains abnormal cells (mosaic level)

• Low level mosaic: A lower percentage of the biopsy contains abnormal cells (typically <50%, although cutoffs vary between laboratories). These embryos generally have the best outcomes.
• High level mosaic: A higher percentage of the biopsy contains abnormal cells (typically >50%). These embryos tend to have lower implantation and live birth rates.

2. What is affected (mosaic type)

• Segmental mosaic: Only part of a chromosome is abnormal. These embryos can have outcomes close to euploid embryos.
• Whole chromosome mosaic: An entire chromosome is abnormal. These embryos generally have lower success rates than segmental mosaics.

Current guidance from PGDIS, ESHRE and ASRM recommends prioritizing low level mosaics over high level mosaics, while also considering embryo quality (higher grades over lower grades). Earlier guidelines also ranked embryos based on the chromosome involved, but more recent guidance has moved away from chromosome-specific ranking because there isn't enough consistent evidence to support it.

Current guidelines also recommend genetic counseling before transferring a mosaic embryo as well as prenatal testing.

Most mosaic embryo transfers result in healthy babies, and confirmed cases of babies born with the same mosaic abnormality appear to be rare. In one study of over 2000 transfers, only about 1.2% of pregnancies had a matching mosaic result.

✅ This post covers the basics. The full article on Remembryo goes into more detail: https://www.remembryo.com/mosaic-embryo

✉️ Like this post? Explore more topics and sign up for my free Friday newsletter to stay updated on the latest IVF research: https://mailchi.mp/remembryo/x27kx5o1sw

A new randomized trial compared natural and medicated frozen embryo transfers (FET) in women who ovulate regularly.

In the study, Geysenbergh et al. (2026) randomized 561 women to one of the two approaches. They found no statistically significant difference in clinical pregnancy rates, with pregnancy occurring in 33.1% of natural FETs and 28.9% of medicated FETs.

However, natural FETs had fewer cancelled transfers (3.9% vs 9.4%), although they required more monitoring visits to detect ovulation. C-sections were also more common after medicated FETs (42.7% vsa 20.2%).

This trial wasn't large enough to compare live birth rates or obstetric outcomes, such as preeclampsia, which some previous studies have found to be more common after medicated FETs.

These results are consistent with a recent meta-analysis of 11 randomized trials, which found similar clinical pregnancy rates but slightly higher live birth rates and lower miscarriage rates with natural FETs in women who ovulate regularly.

✅ This post is a quick look at one study, rather than a full breakdown on Remembryo. Link to the study: https://academic.oup.com/humrep/advance-article-abstract/doi/10.1093/humrep/deag095/8711430?redirectedFrom=fulltext

✉️ Like this post? Get a free weekly summary of the latest IVF research: https://mailchi.mp/remembryo/x27kx5o1sw

July’s IVF Research Roundup is live!

🔹 New study highlights

🔹 IVF news & community Q&A

🔹 ~60 research study summaries (subscribers only)

📌 Post is free to read (no paywall): https://remembryo.com/monthly-ivf-research-roundup-july-2026/

Researchers combined 85 randomized trials and found endometrial scratching improved live birth, while most other IVF add-ons showed unclear benefits.

IVF add-ons are tests, treatments, or procedures used alongside standard IVF in an attempt to improve the chance of pregnancy or having a baby. While many add-ons are widely offered, it's often unclear how well they work.

Lensen et al. (2026) combined the results of 85 randomized trials evaluating ten of the most commonly used IVF add-ons.

The authors carefully evaluated whether each study was trustworthy before including it. They identified 157 potentially eligible randomized trials, but excluded 72 because they weren't registered before the study began or had other issues that could make their results less reliable.

Overall, most IVF add-ons were not supported by strong evidence of improving live birth. Endometrial scratching was the only add-on associated with a higher live birth rate.

Other results include:

• EmbryoGlue: Improved clinical pregnancy.

• PICSI: Reduced miscarriage.

• PGT-A: Reduced miscarriage.

• Acupuncture: Increased both clinical pregnancy and miscarriage, but the evidence was very low quality.

• Most other add-ons: Showed little or no benefit or require more high-quality research.

✅ Check out more details on Remembryo: https://remembryo.com/what-the-latest-evidence-says-about-ten-common-ivf-add-ons/

✉️ Like this post? Get a free weekly summary of the latest IVF research: https://mailchi.mp/remembryo/x27kx5o1sw

Implantation actually requires inflammation.

Inflammation often gets a bad reputation, but it's a normal part of healing. After a cut, immune cells quickly gather at the area to destroy bacteria, clear away damaged cells, coordinate tissue repair, and help form new blood vessels.

Implantation shares many of these same features. The embryo doesn't simply "stick" to the endometrium. It attaches and begins growing into the tissue, which triggers immune cells to gather at the implantation site. These immune cells help coordinate inflammation, remodel the surrounding tissue, and promote the growth of new blood vessels that will eventually become part of the placenta.

This is why the early stage of pregnancy is naturally pro-inflammatory. Rather than being harmful, this carefully controlled inflammation helps the embryo implant and supports early placental development.

As pregnancy progresses, the immune system changes:

• First trimester: Pro-inflammatory (helps the embryo implant)
• Second trimester: Anti-inflammatory (supports the growing baby)
• Third trimester: Pro-inflammatory again (helps start labor)

The goal isn't to have more or less inflammation. The body needs the right amount at the right time. If inflammation is too high, too low, or not well controlled, it may contribute to implantation failure or miscarriage in some patients.

✅ This post covers the basics. The full article on Remembryo goes into more detail: https://remembryo.com/the-role-of-the-immune-system-in-infertility-and-ivf/

✉️ Like this post? Sign up for my free Friday newsletter to stay updated on the latest IVF research: https://mailchi.mp/remembryo/x27kx5o1sw

PGT-A and NIPT are highly accurate screening tests, but they can't guarantee that a baby is free of chromosome abnormalities. In this case report, a 40-year-old woman conceived through IVF after transfer of a euploid embryo and later received a low-risk NIPT result. Her detailed 19-week anatomy ultrasound was also reassuring, with no structural abnormalities or other markers for Down syndrome identified.

At 36 weeks, however, ultrasound showed severe polyhydramnios and a double bubble sign, which suggested duodenal atresia, a condition associated with Down syndrome. The patient was offered amniocentesis but declined, choosing postnatal testing instead. After birth, testing confirmed trisomy 21.

The authors write, "While PGT-A is a screening tool, it is often used to guide decisions with diagnostic consequences, including which embryos are transferred and which are discarded."

This case highlights that PGT-A is a risk-reduction tool rather than a guarantee. Although PGT-A and NIPT are highly accurate, rare false-negative results can occur for a number of biological and technical reasons. One possible explanation is that both tests assess placental cells or DNA rather than the fetus directly.

✅ This post is a quick look at one study, rather than a full breakdown on Remembryo. Link to the study: https://www.fertstertreports.org/article/S2666-3341(26)00110-8/fulltext

✉️ Like this post? Get a free weekly summary of the latest IVF research: https://mailchi.mp/remembryo/x27kx5o1sw

Happy World Embryologist Day!

Today (July 25) is World Embryologist Day, celebrated on the birthday of Louise Brown, the first baby born through IVF in 1978.

It's a day to recognize the embryologists who work behind the scenes to help make IVF possible.

Some patients might not meet their embryology team, but they're the ones who inseminate eggs, check for fertilization, monitor embryo development, perform biopsies when needed, freeze and thaw embryos, and prepare them for transfer. They care for the embryos every step of the way!

As a former embryologist, I know how embryologists sometimes receive less recognition compared with other members of the IVF team, so if you can, consider sending your embryology team a card, a thank you note, coffee/tea, or treats for the lab. Even a simple message can brighten someone's day!

Happy World Embryologist Day to all the embryologists!

Researchers combined the results of 7 randomized trials and found that Lactobacillus-containing probiotics were associated with higher clinical pregnancy rates in women having an embryo transfer.

The reproductive tract naturally contains bacteria, some of which may help support fertility. Because Lactobacillus bacteria are thought to promote a healthy reproductive environment, probiotic supplements have been studied as a way to improve IVF outcomes.

Hiratsuka et al. (2026) combined the results of seven randomized trials to see if Lactobacillus-containing probiotics improve pregnancy rates in women having an embryo transfer.

They found that probiotics were associated with higher clinical pregnancy rates. About 12 more women became pregnant for every 100 women treated. There was no difference in miscarriage rates.

The benefit was seen mainly when probiotics were taken for more than 14 days and in patients without recurrent implantation failure.

One possible explanation is that probiotics may help create a healthier uterine environment for embryo implantation.

However, the results should be interpreted with caution. Five of the seven randomized trials were small, while the two largest trials found no benefit. An earlier meta-analysis that included many of the same trials also found no significant improvement.

Importantly, this meta-analysis looked at clinical pregnancy rather than live birth, so it still isn’t clear if probiotics improve the chance of taking home a baby.

✅ Check out more details on Remembryo: https://remembryo.com/lactobacillus-probiotics-may-improve-pregnancy-rates/

✉️ Like this post? Get a free weekly summary of the latest IVF research: https://mailchi.mp/remembryo/x27kx5o1sw

The Uterine Wall of Fame (UWOF) is a collection of real IVF success stories from people with difficult fertility journeys -- low-grade embryos, repeated failures, low AMH, mosaic results, and more. 

UWOF #39 is one of those stories. Eight years, three miscarriages, and eight embryo transfers finally led to a healthy baby girl. In October 2025, Laura welcomed her daughter, Aubree. 

✅ Visit the UWOF to read this story and others like it (free to access & no subscription required): https://remembryo.com/uwof39-after-8-years-and-8-transfers-we-met-aubree/

💌 Have a story of your own? Can be anonymous or named: https://www.remembryo.com/uterine-wall-of-fame-submission-form/

⚠️ These are personal stories, not medical advice or scientific evidence. A success story isn't proof of what made the difference. Always discuss treatment decisions with your fertility specialist.

Does transferring a cleavage stage or blastocyst stage embryo affect the chance of having a boy?

Perlman et al. (2021) analyzed nearly 100,000 frozen embryo transfers (FETs) from the US SART registry to see whether embryo stage affected the baby's sex.

Cleavage stage (~day 3) transfers resulted in 50.5% male births, while blastocyst stage (~day 5) transfers resulted in 51.9% male births.

Although the difference was statistically significant, it was small (corresponding to about 1 to 2 additional boys per 100 live births after blastocyst transfer). This isn't enough to influence embryo selection (PGT-A is needed to determine embryo sex), but it does suggest that blastocyst transfer is associated with a slightly higher chance of having a boy.

Other studies, including a 2022 meta-analysis, have reported similar findings.

Researchers aren't sure why this happens. One possibility is that male embryos develop slightly faster than female embryos, making them more likely to reach the blastocyst stage first. Since clinics generally transfer the most advanced-looking embryo, this could slightly increase the chance of transferring a male embryo. However, the exact reason isn't clear.

✅ Check out the details on Remembryo: https://remembryo.com/do-male-embryos-grow-faster-than-female-embryos/

✉️ Like this post? Get a free weekly summary of the latest IVF research: https://mailchi.mp/remembryo/x27kx5o1sw

A new eye-tracking study by Asai et al. (2026) compared where experienced embryologists and beginners looked while performing ICSI. The researchers wanted to understand what makes experienced embryologists more efficient.

Overall, experts completed the procedure more quickly, made fewer unnecessary eye movements, and showed more consistent visual attention than beginners.

The third page of the post shows heat maps of where participants looked during ICSI. Red areas represent where they spent the most time looking, while green areas indicate shorter attention.

During STEP 1 (egg rotation), the goal is to rotate the egg so the polar body is positioned at the 12 or 6 o'clock position before injection. The polar body acts as a landmark because the egg's chromosome-containing spindle is usually nearby, and placing it in this position helps embryologists inject the sperm while minimizing the chance of damaging the spindle. In the study, experts kept their attention focused on the polar body throughout this step, while beginners looked around more and often focused on the injection pipette instead.

During STEP 2 (the sperm injection), the embryologist inserts the injection pipette through the egg's outer shell and membrane to place a single sperm inside the egg. At this stage, the eye movement patterns of experts and beginners were much more similar.

While this was a simulation study using pig eggs rather than human eggs, the results could help improve embryologist training and may eventually contribute to AI systems that assist with ICSI.

✅ This post is a quick look at one study, rather than a full breakdown on Remembryo. Link to the study: https://www.nature.com/articles/s41598-026-57054-8

✉️ Like this post? Get a free weekly summary of the latest IVF research: https://mailchi.mp/remembryo/x27kx5o1sw

Researchers combined the results of 9 studies and found that embryos from 0PN zygotes had similar pregnancy outcomes to embryos from normally fertilized (2PN) zygotes, despite being less likely to develop into blastocysts.

In IVF, fertilization is confirmed by seeing two pronuclei (2PN) in the fertilized egg (zygote) a day after insemination. Because these structures are only visible briefly, some normally fertilized zygotes may be mistakenly classified as 0PN (no visible pronuclei).

Chan et al. (2026) performed a meta-analysis and combined the results of 9 studies to see how embryos from 0PN zygotes compare to normally fertilized 2PN zygotes.

They found that embryos from 0PN zygotes that reach the blastocyst stage have pregnancy outcomes similar to embryos from 2PN zygotes, although they're less likely to develop into blastocysts in the first place.

One possible explanation is that some 0PN zygotes are actually "false" 0PNs, which are normally fertilized zygotes whose pronuclei formed or disappeared outside the standard 16–18 hour fertilization check.

They also compared IVF- and ICSI-derived 0PN zygotes. Pregnancy outcomes were lower for embryos from IVF-derived 0PN zygotes, but not ICSI-derived 0PN zygotes.

This may be because IVF-derived 0PN zygotes are more likely to include embryos resulting from polyspermy (fertilization by more than one sperm), although the subgroups were smaller and this finding should be interpreted with caution, the authors note.

✅ Check out more details on Remembryo: https://remembryo.com/pregnancy-outcomes-similar-for-embryos-from-0pn-and-2pn-zygotes/

✉️ Like this post? Get a free weekly summary of the latest IVF research: https://mailchi.mp/remembryo/x27kx5o1sw

The European Society of Human Reproduction and Embryology (ESHRE) wrapped up their 42nd annual meeting last week, focusing on the latest developments in IVF and ART.

Here's some of the highlights I selected:

➡️ An international registry study from 46 IVF centers found that whole-chromosome aneuploid embryos did not result in any live births, while 20% of segmental aneuploid embryos did.

➡️ A randomized trial found that PRP did not improve embryo quality, ovarian response, or pregnancy outcomes in women with diminished ovarian reserve. A second randomized trial in a similar population reported similar results.

➡️ A meta-analysis found that GLP-1 receptor agonist exposure before conception or during the first trimester was not associated with an increased risk of major birth defects or adverse pregnancy outcomes.

➡️ A meta-analysis found that Lactobacillus-containing probiotics were associated with higher clinical pregnancy rates, particularly when treatment lasted more than 14 days.

➡️ A randomized trial found that 150 IU vs. 225 IU recombinant FSH resulted in similar live birth rates, although the 150 IU dose produced higher blastocyst rates in predicted normal responders.

➡️ Researchers compared IVF costs across 22 countries and found that more affordable treatment was associated with greater use of IVF and more babies born through assisted reproduction.

Note that these results come from conference abstracts, which are preliminary and may not yet have undergone peer review.

✅ Check out all the highlights (and links to the original research) on Remembryo: https://remembryo.com/highlights-from-eshres-42nd-annual-meeting-2026/

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The sperm microbiome is the collection of bacteria naturally found in semen, and researchers are beginning to investigate if it can influence male fertility.

In a new study, Renouf et al. (2026) found that several lifestyle factors, like BMI, diet and smoking, were associated with differences in the sperm microbiome. They also found that men whose partners didn't get pregnant had higher levels of Staphylococcus bacteria in their sperm samples.

Based on these findings, the researchers suggest that lifestyle changes could influence the sperm microbiome, which might eventually help improve male fertility.

While it's interesting that lifestyle factors were linked to changes in the sperm microbiome, this is very early research so it's not clear if these changes can actually improve fertility. To show that, researchers would need studies demonstrating that a lifestyle change alters the sperm microbiome and that those changes lead to more pregnancies.

✅ This post is a quick look at one study, rather than a full breakdown on Remembryo. Link to the study: https://www.nature.com/articles/s41598-026-57767-w

✉️ Like this post? Get a free weekly summary of the latest IVF research: https://mailchi.mp/remembryo/x27kx5o1sw