BMI and other factors affecting embryo transfer outcomes

Dr. Beth Taylor

February 20, 2022

If I could just do initial consults and pregnancy scans my job would be pretty easy but alas that’s not how life works.  Failed treatment cycles, challenging diagnoses, and second opinions are all part of the work.  If I am truly honest, there are parts of these hard times I enjoy but not failed cycles.


When this month’s Fertility and Sterility journal came out, I read the article on factors affecting live birth rates with egg donor treatment with interest (Reference: Williams RS, Ellis DD, Wilkinson EA, Kramer JM, Datta S, Guzick DS. Factors affecting live birth rates in donor oocytes from commercial egg banks vs. program egg donors: an analysis of 40,485 cycles from the Society for Assisted Reproductive Technology registry in 2016-2018. Fertil Steril. 2022 Feb;117(2):339-348.).  


Not all egg donor embryo transfers are successful.  About 65% are successful; the rest we look for reasons why.  Most of the time we attribute failed egg donor cycles to abnormal embryos we know about 30-35% of egg donor embryos are chromosomal abnormal.  Are there other factors that can harm the success rate?


This study examined about 19,000 egg donor embryo transfers in the USA between 2016-2018.  There were two categories: own clinic egg donors and commercial banks.  There were no dramatic differences in the two categories.   


They found that the two most powerful predictors of egg donor embryo transfer outcome was the age and BMI of the person receiving the embryo.  If the recipient’s age was over 45, there was a decline in live birth rate (of about 5% - not all that large, but still meaningful).  If the recipient’s BMI was over 30 kg/m2 there was also a decline in live birth rates.  


Two other factors also mattered: if the egg donor’s lot was > 16 eggs and blastocysts were transferred there were higher pregnancy rates.


Of these four factors, BMI is the only factor under the recipient’s control.  


This naturally leads to the next question which is how can we help people bring their BMI lower to improve their egg donor embryo transfer pregnancy rates?


This brings me to my next area of consideration: weight loss medication.


Glucagon-like Peptide-1 (GLP-1) is released from cells in the gastrointestinal tract.  GLP-1 delays gastric emptying (so you feel full), decreases the bowel’s absorption of glucose, improves the activity of insulin, and suppresses the appetite centre of the brain.  For these reasons GLP-1 medications cause weight loss.  These medications (e.g. Ozempic, Saxenda) are given by injection daily or weekly and typically cause weight loss of about 1 lb per week.  The common side effects include gastrointestinal upset (rare severe effects are gallbladder disease, kidney disease and pancreatitis).


I have prescribed these medications to several women who are struggling to lose weight to improve their fertility with good success when combined with exercise and lifestyle changes.


They are expensive, but some drug plans cover some/all of the cost. These medications should NOT be taken in pregnancy and should be stopped for 2 months prior to a planned pregnancy or embryo transfer.


There is no doubt that the best way to lose weight is with diet and exercise, but we can all agree it’s hard to do, and help through medications can make it less frustrating and more successful. Something to consider and discuss with your doctor.  The aim is to optimize your health and the success of an embryo transfer.

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