Embryoman (2025)

01/07/2025

Growing embryos to day 7 can help patients expand the number of blastocysts they get from an IVF cycle.

But even when they’re euploid and good quality, day 7 live birth rates are lower than day 5 or 6 blastocysts. Why this is isn't clear!

In a new study, Blair McCallie and colleagues set out to explore this, and compared gene expression in day 5 and day 7 euploid embryos.

They found many differences in how genes were expressed, especially in the inner cell mass (ICM), which is the part of the blastocyst that becomes the fetus.

Day 7 ICMs showed signs of metabolic stress, disrupted cellular signaling, and changes in gene expression that could affect implantation. Day 7 embryos also showed increased expression of genes linked to cell death.

These differences might help explain why day 7 embryos have lower success rates, even when they are higher quality and are euploid. It’s still early-stage research, but research like this could eventually lead to better embryo culture conditions and better outcomes for patients!

✅ Check out all the details on Remembryo, link is in the comments.

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𝐇𝐚𝐯𝐞 𝐲𝐨𝐮 𝐞𝐯𝐞𝐫 𝐡𝐚𝐝 𝐚 𝐝𝐚𝐲 𝟕 𝐛𝐥𝐚𝐬𝐭𝐨𝐜𝐲𝐬𝐭? 𝐃𝐢𝐝 𝐢𝐭 𝐰𝐨𝐫𝐤? 𝘕𝘰𝘵𝘦 𝘵𝘩𝘢𝘵 𝘵𝘩𝘪𝘴 𝘱𝘰𝘴𝘵 𝘪𝘴 𝘧𝘳𝘰𝘮 𝘮𝘺 𝘱𝘶𝘣𝘭𝘪𝘤-𝘧𝘢𝘤𝘪𝘯𝘨 𝘱𝘢𝘨𝘦. 𝘛𝘩𝘦 𝘴𝘢𝘮𝘦 𝘱𝘰𝘴𝘵 𝘤𝘢𝘯 𝘣𝘦 𝘧𝘰𝘶𝘯𝘥 𝘪𝘯 𝘮𝘺 𝘱𝘳𝘪𝘷𝘢𝘵𝘦 𝘨𝘳𝘰𝘶𝘱, 𝘸𝘩𝘪𝘤𝘩 𝘐'𝘭𝘭 𝘭𝘪𝘯𝘬 𝘪𝘯 𝘵𝘩𝘦 𝘤𝘰𝘮𝘮𝘦𝘯𝘵𝘴.

30/06/2025

Scientists have created male mice from two s***m cells, without using any egg DNA, and those mice went on to have their own babies, marking a major step toward same-sex couples one day having children who share both parents’ DNA.

The team removed the nucleus from an egg and inserted two s***m, then used a technique called epigenome editing to reprogram the DNA to allow normal development.

Only 2 of the 259 embryos survived, both growing into male mice that later fathered healthy pups after mating with females. This proves that combining two s***m in an egg can produce fertile, healthy offspring, though the method is highly inefficient and technically complex.

Experts say this method won’t be possible in humans anytime soon, since it would require a large number of eggs and surrogates and raises ethical and safety concerns.

Still, the study shows that editing epigenetic signals (without changing the DNA itself) could be a way to make same-sex reproduction possible someday.

Edit. A lot of people in the comments are pointing out that “you still need an egg.” That’s true, but the egg can come from a donor and the DNA from the egg is removed (except the mitochondrial DNA -- more on this below). The breakthrough here is that two males (and potentially two females) could both contribute DNA to create a child. That’s never been possible before, and it’s a major step forward for same-sex couples hoping to have genetically related children.

The egg provides mitochondria, which are tiny "organelles" inside our cells that act like batteries to power cellular activities like fertilization and embryo development. Mitochondria each have their own DNA, with 37 genes mainly involved in supporting energy production by mitochondria. The need for an energy source is one of the reasons why the egg is still used in the procedure. The s***m contributes nuclear DNA, which includes about 25,000 genes that shape most of our characteristics and also help regulate mitochondrial function. In this procedure, the egg’s nuclear DNA is removed, so the resulting embryo contains nuclear DNA from the two s***m and mitochondrial DNA from the egg. When we talk about genetic inheritance, we are usually referring to nuclear DNA, not mitochondrial DNA.

This research isn’t about minimizing the role of the egg, it’s about making it possible for two people, likely two men (or eventually two women), to both contribute nuclear DNA to create a child.

✅ Check out all the details on New Scientist, link is in the comments.

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𝘕𝘰𝘵𝘦 𝘵𝘩𝘢𝘵 𝘵𝘩𝘪𝘴 𝘱𝘰𝘴𝘵 𝘪𝘴 𝘧𝘳𝘰𝘮 𝘮𝘺 𝘱𝘶𝘣𝘭𝘪𝘤-𝘧𝘢𝘤𝘪𝘯𝘨 𝘱𝘢𝘨𝘦. 𝘛𝘩𝘦 𝘴𝘢𝘮𝘦 𝘱𝘰𝘴𝘵 𝘤𝘢𝘯 𝘣𝘦 𝘧𝘰𝘶𝘯𝘥 𝘪𝘯 𝘮𝘺 𝘱𝘳𝘪𝘷𝘢𝘵𝘦 𝘨𝘳𝘰𝘶𝘱, 𝘸𝘩𝘪𝘤𝘩 𝘐'𝘭𝘭 𝘭𝘪𝘯𝘬 𝘪𝘯 𝘵𝘩𝘦 𝘤𝘰𝘮𝘮𝘦𝘯𝘵𝘴.

30/06/2025

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30/06/2025

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Our unique approach sets us apart:

✓ Founded by embryologists who understand the science and stakes involved
✓ Hand-carry transport ensures genetic materials are handled with care
✓ Constant temperature monitoring at -196°C throughout transport
✓ Dedicated concierge service for seamless coordination and real-time updates
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We're proud of our reputation for delivering exceptional service and results. If you have questions about transporting genetic materials or would like to learn more about our services, we'd love to hear from you.

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27/06/2025

A new randomized controlled trial (RCT) examined probiotic use in IVF patients around the time of embryo transfer.

In IVF patients, vaginal dysbiosis (with abnormal vaginal microbiota) may let harmful bacteria reach the uterus and possibly interfere with embryo implantation and early pregnancy. Some researchers have suggested that replacing these bacteria with beneficial ones, using antibiotics and probiotics, might improve outcomes.

In this new RCT by Thor Haahr and colleagues, IVF patients with vaginal dysbiosis were treated with antibiotics followed by a Lactobacillus crispatus probiotic. However, they found no difference in pregnancy rates compared to placebo.

✅ I haven't reviewed this one in detail, but you can find the original study in the comments.

✉️ Want to stay up to date on new IVF research? Follow me and send me a DM with your email and I'll sign you up to my weekly newsletter.

𝐇𝐚𝐯𝐞 𝐲𝐨𝐮 𝐭𝐫𝐢𝐞𝐝 𝐩𝐫𝐨𝐛𝐢𝐨𝐭𝐢𝐜𝐬 𝐭𝐨 𝐢𝐦𝐩𝐫𝐨𝐯𝐞 𝐈𝐕𝐅 𝐨𝐮𝐭𝐜𝐨𝐦𝐞𝐬? 𝐃𝐢𝐝 𝐢𝐭 𝐰𝐨𝐫𝐤? 𝘕𝘰𝘵𝘦 𝘵𝘩𝘢𝘵 𝘵𝘩𝘪𝘴 𝘱𝘰𝘴𝘵 𝘪𝘴 𝘧𝘳𝘰𝘮 𝘮𝘺 𝘱𝘶𝘣𝘭𝘪𝘤-𝘧𝘢𝘤𝘪𝘯𝘨 𝘱𝘢𝘨𝘦. 𝘛𝘩𝘦 𝘴𝘢𝘮𝘦 𝘱𝘰𝘴𝘵 𝘤𝘢𝘯 𝘣𝘦 𝘧𝘰𝘶𝘯𝘥 𝘪𝘯 𝘮𝘺 𝘱𝘳𝘪𝘷𝘢𝘵𝘦 𝘨𝘳𝘰𝘶𝘱, 𝘸𝘩𝘪𝘤𝘩 𝘐'𝘭𝘭 𝘭𝘪𝘯𝘬 𝘪𝘯 𝘵𝘩𝘦 𝘤𝘰𝘮𝘮𝘦𝘯𝘵𝘴.

26/06/2025

Embryologists check for fertilization the day after insemination by looking for two pronuclei (2PN), one from the egg and one from the s***m. This usually means fertilization happened correctly.

Sometimes, only one pronucleus (1PN) is seen, which suggests abnormal fertilization. These embryos are often discarded because they might have the wrong number of chromosomes.

But some studies using PGT have found that 1PN embryos can be diploid and euploid, meaning they have the right number of chromosomes from both parents, suggesting they can be normal and capable of leading to healthy pregnancies.

A new meta-analysis by Tammy Lee and colleagues combined the results of 24 studies that compared 1PN and 2PN embryos in development, pregnancy outcomes, and newborn outcomes.

Untested 1PN embryos had lower live birth and blastocyst formation rates than 2PNs, but if they tested euploid then live birth rates were similar.

Euploid rates were about the same for 1PN and 2PN embryos, and newborn outcomes were also similar.

This is encouraging for patients with 1PNs, especially if they test as both diploid and euploid, but not all PGT platforms can confirm both, so caution is needed if a 1PN is only confirmed as euploid.

Without time-lapse imaging, clinics may misclassify 1PNs if the second pronucleus forms late or disappears early. The authors recommend that embryologists recheck at a second time point to help prevent misclassifications.

✅ Check out all the details on Remembryo, link is in the comments.

✉️ Want to stay up to date on new IVF research? Follow me and send me a DM with your email and I'll sign you up to my weekly newsletter.

𝐇𝐚𝐯𝐞 𝐲𝐨𝐮 𝐞𝐯𝐞𝐫 𝐡𝐚𝐝 𝐚𝐧𝐲 𝟏𝐏𝐍𝐬? 𝐃𝐢𝐝 𝐲𝐨𝐮 𝐭𝐫𝐲 𝐭𝐫𝐚𝐧𝐬𝐟𝐞𝐫𝐫𝐢𝐧𝐠 𝐭𝐡𝐞𝐦? 𝘕𝘰𝘵𝘦 𝘵𝘩𝘢𝘵 𝘵𝘩𝘪𝘴 𝘱𝘰𝘴𝘵 𝘪𝘴 𝘧𝘳𝘰𝘮 𝘮𝘺 𝘱𝘶𝘣𝘭𝘪𝘤-𝘧𝘢𝘤𝘪𝘯𝘨 𝘱𝘢𝘨𝘦. 𝘛𝘩𝘦 𝘴𝘢𝘮𝘦 𝘱𝘰𝘴𝘵 𝘤𝘢𝘯 𝘣𝘦 𝘧𝘰𝘶𝘯𝘥 𝘪𝘯 𝘮𝘺 𝘱𝘳𝘪𝘷𝘢𝘵𝘦 𝘨𝘳𝘰𝘶𝘱, 𝘸𝘩𝘪𝘤𝘩 𝘐'𝘭𝘭 𝘭𝘪𝘯𝘬 𝘪𝘯 𝘵𝘩𝘦 𝘤𝘰𝘮𝘮𝘦𝘯𝘵𝘴.

25/06/2025

Insulin resistance often comes up with PCOS, where it affects 35 to 80% of patients, but many people without PCOS have it too, often without knowing. This so-called “silent” insulin resistance can go undetected unless specifically tested for.

A new study by Ana Belén Albert and colleagues compared IVF outcomes in women with or without insulin resistance, who didn't have PCOS or diabetes and weren't obese.

After an oral glucose tolerance test, they found that nearly one in three of these women had insulin resistance.

Those with insulin resistance had lower live birth rates and higher miscarriage rates, which improved with metformin (a medication that boosts insulin sensitivity). These insulin-resistant patients had about 4x the live birth rate when treated with metformin!

All patients used donor eggs, suggesting that the uterus, and not the egg, was involved in this lower success.

Biologically, this may relate to how insulin regulates glucose uptake and the buildup of energy stores (glycogen) in the endometrium, which is critical for implantation.

Previous studies have shown that insulin resistance worsens IVF outcomes in women with PCOS, but evidence in non-PCOS women is limited and mixed.

Overall, this study suggests it may be worth screening for insulin resistance during IVF, even in people who seem healthy.

✅ Check out all the details on Remembryo, link is in the comments.

✉️ Want to stay up to date on new IVF research? Follow me and send me a DM with your email and I'll sign you up to my weekly newsletter.

𝐇𝐚𝐯𝐞 𝐲𝐨𝐮 𝐛𝐞𝐞𝐧 𝐬𝐜𝐫𝐞𝐞𝐧𝐞𝐝 𝐟𝐨𝐫 𝐢𝐧𝐬𝐮𝐥𝐢𝐧 𝐫𝐞𝐬𝐢𝐬𝐭𝐚𝐧𝐜𝐞 𝐝𝐮𝐫𝐢𝐧𝐠 𝐈𝐕𝐅, 𝐨𝐫 𝐡𝐚𝐯𝐞 𝐲𝐨𝐮 𝐭𝐫𝐢𝐞𝐝 𝐦𝐞𝐭𝐟𝐨𝐫𝐦𝐢𝐧? 𝘕𝘰𝘵𝘦 𝘵𝘩𝘢𝘵 𝘵𝘩𝘪𝘴 𝘱𝘰𝘴𝘵 𝘪𝘴 𝘧𝘳𝘰𝘮 𝘮𝘺 𝘱𝘶𝘣𝘭𝘪𝘤-𝘧𝘢𝘤𝘪𝘯𝘨 𝘱𝘢𝘨𝘦. 𝘛𝘩𝘦 𝘴𝘢𝘮𝘦 𝘱𝘰𝘴𝘵 𝘤𝘢𝘯 𝘣𝘦 𝘧𝘰𝘶𝘯𝘥 𝘪𝘯 𝘮𝘺 𝘱𝘳𝘪𝘷𝘢𝘵𝘦 𝘨𝘳𝘰𝘶𝘱, 𝘸𝘩𝘪𝘤𝘩 𝘐'𝘭𝘭 𝘭𝘪𝘯𝘬 𝘪𝘯 𝘵𝘩𝘦 𝘤𝘰𝘮𝘮𝘦𝘯𝘵𝘴.

24/06/2025

Study films embryos defending themselves from bacterial infection

In a new study, Joan Roncero-Carol and colleagues looked at how embryos defend themselves from bacteria.

Using zebrafish embryos and human cells, they showed that the outer layer (trophectoderm) of the embryo can actually "eat" bacteria.

When bacteria like E. coli come into contact with trophectoderm cells, the embryo cells reach out with little finger-like projections to wrap around and swallow the bacteria, similar to how immune cells work.

Once inside, the bacteria are passed through a series of compartments where they’re broken down and destroyed.

A single trophectoderm cell was able to ingest about 30 bacteria in 40 minutes.

The researchers observed two ways this can happen: either by scooping bacteria up with broad membrane ruffles, or by using protrusions to "zipper" up the bacterium.

This shows that even at this early stage, embryos have a built-in way to protect themselves from infection!

✅ I haven't reviewed this one in detail, but you can find the original study in the comments.

✉️ Want to stay up to date on new IVF research? Follow me and send me a DM with your email and I'll sign you up to my weekly newsletter.

𝘕𝘰𝘵𝘦 𝘵𝘩𝘢𝘵 𝘵𝘩𝘪𝘴 𝘱𝘰𝘴𝘵 𝘪𝘴 𝘧𝘳𝘰𝘮 𝘮𝘺 𝘱𝘶𝘣𝘭𝘪𝘤-𝘧𝘢𝘤𝘪𝘯𝘨 𝘱𝘢𝘨𝘦. 𝘛𝘩𝘦 𝘴𝘢𝘮𝘦 𝘱𝘰𝘴𝘵 𝘤𝘢𝘯 𝘣𝘦 𝘧𝘰𝘶𝘯𝘥 𝘪𝘯 𝘮𝘺 𝘱𝘳𝘪𝘷𝘢𝘵𝘦 𝘨𝘳𝘰𝘶𝘱, 𝘸𝘩𝘪𝘤𝘩 𝘐'𝘭𝘭 𝘭𝘪𝘯𝘬 𝘪𝘯 𝘵𝘩𝘦 𝘤𝘰𝘮𝘮𝘦𝘯𝘵𝘴.

23/06/2025

After an embryo transfer, does flying have any impact on success rates?

Modern air travel involves pressurized cabins, lower humidity, and mild radiation exposure, but is considered safe for pregnant patients.

A new study by João Antonio Dias Jr and colleagues compared embryo transfer outcomes for patients who did or didn't fly* after transfer, and found no differences.

*Patients lived more than 400 km from the IVF clinic, so the authors assumed they flew home.

✅ I haven't reviewed this one in detail, but you can find the original study in the comments.

✉️ Want to stay up to date on new IVF research? Follow me and send me a DM with your email and I'll sign you up to my weekly newsletter.

𝐇𝐚𝐯𝐞 𝐲𝐨𝐮 𝐟𝐥𝐨𝐰𝐧 𝐚𝐟𝐭𝐞𝐫 𝐚𝐧 𝐞𝐦𝐛𝐫𝐲𝐨 𝐭𝐫𝐚𝐧𝐬𝐟𝐞𝐫? 𝐀𝐧𝐲 𝐜𝐨𝐧𝐜𝐞𝐫𝐧𝐬? 𝘕𝘰𝘵𝘦 𝘵𝘩𝘢𝘵 𝘵𝘩𝘪𝘴 𝘱𝘰𝘴𝘵 𝘪𝘴 𝘧𝘳𝘰𝘮 𝘮𝘺 𝘱𝘶𝘣𝘭𝘪𝘤-𝘧𝘢𝘤𝘪𝘯𝘨 𝘱𝘢𝘨𝘦. 𝘛𝘩𝘦 𝘴𝘢𝘮𝘦 𝘱𝘰𝘴𝘵 𝘤𝘢𝘯 𝘣𝘦 𝘧𝘰𝘶𝘯𝘥 𝘪𝘯 𝘮𝘺 𝘱𝘳𝘪𝘷𝘢𝘵𝘦 𝘨𝘳𝘰𝘶𝘱, 𝘸𝘩𝘪𝘤𝘩 𝘐'𝘭𝘭 𝘭𝘪𝘯𝘬 𝘪𝘯 𝘵𝘩𝘦 𝘤𝘰𝘮𝘮𝘦𝘯𝘵𝘴.

22/06/2025

(Advertisement by LifeParcel)

At LifeParcel, we understand the importance of meticulous care in transporting genetic materials between clinics. That's why we've built a service that prioritizes precision, reliability, and peace of mind.

Our unique approach sets us apart:

✓ Founded by embryologists who understand the science and stakes involved
✓ Hand-carry transport ensures genetic materials are handled with care
✓ Constant temperature monitoring at -196°C throughout transport
✓ Dedicated concierge service for seamless coordination and real-time updates
✓ Proven track record: 2,500+ successful missions with zero incidents

We're proud of our reputation for delivering exceptional service and results. If you have questions about transporting genetic materials or would like to learn more about our services, we'd love to hear from you.

Get a quote by visiting the link in the comments. Special offer: Use code EMBRYOMAN to receive 10% off through August 4th.

18/06/2025

*See the update at the end of this post for new information.

The American Society for Reproductive Immunology (ASRI) has released the first evidence-based clinical guidelines for immunological treatment of recurrent pregnancy loss (RPL).

RPL is defined as two or more pregnancy losses, and in unexplained cases, it may be linked to immune issues like high NK cells, Th1/Th2 imbalance, or autoantibodies.

Recommended treatments include corticosteroids (eg. prednisone) but only in patients with confirmed immune abnormalities, along with vitamin D supplementation (if deficient) and heparin plus aspirin for those with antiphospholipid syndrome (APS).

Conditionally recommended treatments include IVIG for patients with multiple losses and immune abnormalities, corticosteroids for those without immune abnormalities, LIT (outside the US with proper immune screening), and hydroxychloroquine for autoimmune conditions or placental inflammation.

Treatments with unclear benefit include intralipids, calcineurin inhibitors (tacrolimus), G-CSF (neupogen), TNF-α inhibitors (adalimumab), and hCG.

Some immune treatments may help certain RPL patients with immune issues, but many are still unproven and used inconsistently.

The ASRI stresses that immunotherapy should be used only when immune problems are confirmed, and not given without clear evidence.

Update: After posting this, I looked more closely at the studies behind ASRI’s corticosteroid recommendation. Some of the evidence they relied on had issues, including a meta-analysis that used non-existent data from a study protocol. I've written a letter to the editor so it can be addressed.

I'll also add that other more well-known assisted reproduction groups, including the HFEA, ESHRE and ASRM, do not recommend immunotherapies due to a lack of high-quality evidence. Because of this, and the data quality concerns described above, the ASRI recommendations should be interpreted with caution.

✅ Check out all the details on Remembryo, link is in the comments.

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𝐇𝐚𝐯𝐞 𝐲𝐨𝐮 𝐮𝐬𝐞𝐝 𝐚𝐧𝐲 𝐢𝐦𝐦𝐮𝐧𝐞 𝐭𝐫𝐞𝐚𝐭𝐦𝐞𝐧𝐭𝐬 𝐟𝐨𝐫 𝐑𝐏𝐋? 𝐃𝐢𝐝 𝐢𝐭 𝐰𝐨𝐫𝐤? 𝘕𝘰𝘵𝘦 𝘵𝘩𝘢𝘵 𝘵𝘩𝘪𝘴 𝘱𝘰𝘴𝘵 𝘪𝘴 𝘧𝘳𝘰𝘮 𝘮𝘺 𝘱𝘶𝘣𝘭𝘪𝘤-𝘧𝘢𝘤𝘪𝘯𝘨 𝘱𝘢𝘨𝘦. 𝘛𝘩𝘦 𝘴𝘢𝘮𝘦 𝘱𝘰𝘴𝘵 𝘤𝘢𝘯 𝘣𝘦 𝘧𝘰𝘶𝘯𝘥 𝘪𝘯 𝘮𝘺 𝘱𝘳𝘪𝘷𝘢𝘵𝘦 𝘨𝘳𝘰𝘶𝘱, 𝘸𝘩𝘪𝘤𝘩 𝘐'𝘭𝘭 𝘭𝘪𝘯𝘬 𝘪𝘯 𝘵𝘩𝘦 𝘤𝘰𝘮𝘮𝘦𝘯𝘵𝘴.

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