This is one of the most heartbreaking moments; a patient is told they have no viable embryos available for a transfer upon completing a round of IVF. After an egg retrieval, the clinic embryologist will send updates on the fertilization rate, day 3 progress and the final embryo count on days 5,6, or 7. This is an incredibly nerve-wracking and stressful time for patients.

Embryo Arrest

It is normal to experience a drop-off at each point, the question becomes how much. After all that anticipation, all the drugs, all the appointments, it is entirely possible to end up with no embryos.

Rarely I’ll see women who have no viable eggs after an egg retrieval, either the follicles were empty, or the eggs too fragile to fertilize. What is more common, and so difficult, is to get the phone call saying none of the embryos survived and made it to day 5. So why do embryos arrest? 

Common Causes

  1. Egg Quality- Low egg quality and diminished ovarian reserve are some of the reasons why embryos might not make it to the blastocyst stage. Let’s go back to high school science and mitochondria. Mitochondria are referred to as the powerhouse of the cell. Highly efficient mitochondria tend to produce higher equality eggs. In one study, levels of mitochondrial DNA were actually higher in poor-quality embryos. Researchers believe that this is a compensatory mechanism, whereby the embryo needs more mitochondria due to poor ATP production and mitochondrial efficiency. Some labs will provide a MitoScore when PGT-A (genetic testing) is performed on embryos. A lower score, <20, has been associated with higher clinical pregnancy rates. 
  2. Sperm Quality- It’s not just about the eggs! Higher DNA fragmentation in sperm can also cause embryos to arrest. After an egg is fertilized, the sperm tends to take over during later embryo development. A large drop off in embryos between days 3-5 can be due to high DNA fragmentation. DNA fragmentation tends to be higher in males who are obese, who smoke and consume large amounts of alcohol. Making healthier lifestyle choices, along with supplementation of key antioxidants, can lower DNA fragmentation. 
  3. Abnormal Chromosomes- Another reason why embryos arrest is due to abnormal chromosomes or aneuploid embryos. Aneuploid embryos contain the incorrect number of chromosomes, either too few or too many. The biggest risk factor for aneuploidy is maternal age. As you can see in the graph below, rates of aneuploidy increase significantly after age 35. In one small study, researchers found that almost 70% of all embryos that arrested exhibited chromosomal abnormalities. 

What’s Next?

Although we cannot change our age, many factors that impact egg and sperm quality can be modified through diet and lifestyle changes. Working with a Naturopathic Doctor who has a strong clinical interest in fertility care can help optimize egg/sperm health before your next IVF cycle. 

 

References

https://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1005241

https://www.sciencedirect.com/science/article/abs/pii/S147264831930639X

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5714603/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4671381/

https://www.fertstert.org/article/S0015-0282(13)03257-3/fulltext

https://www.fertstert.org/article/S0015-0282(15)02246-3/abstract