It has long been known that a woman's weight can influence the outcome of IVF, now Dads need to trim excess pounds before trying to conceive too.
Research (1) has shown that when the male partner is overweight, the chances of IVF succeeding is far less that when the male partner has a normal BMI (body mass index). Such men however are in the minority as more than half of the US male population is technically overweight.
An American study from Albert Einstein College of Medicine has shown that a 5 unit increase in a man's BMI can cause a significant drop in the chances of IVF resulting in pregnancy. If a man's BMI was over 25 chances of conceiving dropped from 49.1% to 34.3%.
Not sure what your man's body mass index is? It's a simple calculation based upon weight and height, it's easy to find a body mass index calculator online and check out his numbers.
Your body mass index is considered 'normal' if it is between 18.5 and 24.9. A person is considered to be overweight if the body mass index is between 25 and 29.9 and obese when the BMI is between 30 and 34.9. If your guy is in the overweight category, he is not alone, according national surveys approximately 59% of men have a BMI over 25.
Another similar study of 290 IVF cycles showed a similarly significant drop in pregnancy rates (53.2% vs. 33.6%) when the male partner had a BMI over 25, but also found that the effects of obesity may be mitigated by using ICSI. This study concluded that:
"In this cohort, overweight status of the male partner was independently associated with decreased likelihood of clinical pregnancy after in vitro fertilization but not after intracytoplasmic sperm injection. A detrimental impact of higher male body mass was observed after adjusting for sperm concentration, suggesting that intracytoplasmic sperm injection may overcome some obesity related impairment of sperm-egg interaction."
The connection between overweight males and poor IVF results is yet to be teased out by further studies. The quality of sperm and embryos were similar whether men were overweight or normal weight leaving unanswered questions regarding why a man's weight makes such a huge difference.
The head researchers (1) speculated that an increase in sperm DNA fragmentation may be to blame. Increasingly, studies are highlighting the importance of sperm DNA integrity to IVF success which - if it is the culprit - is a factor that responds very favorably to increased antioxidant intake. Previous studies have confirmed that overweight men are more likely to have higher levels of sperm DNA fragmentation.
Before you - and your partner - pursue IVF loosing excess pounds and restoring an ideal body mass index could significantly boost your chances of conceiving. Similarly, if you are trying to conceive naturally helping your guy to loose excess weight could help you to conceive more successfully.
One caveat, when choosing a weight loss program make sure that it emphasizes eating plenty of fresh fruits and vegetables - preferably organic -to keep antioxidant intake high. Very restrictive diets in the months leading up to IVF could cause nutrient deficiencies which themselves could adversely affect both male and female fertility.
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Merhi Z, et al "Clinical pregnancy rate but not embryo quality is reduced following IVF-ET in couples with overweight male partners" ASRM 2010; Abstract P-338.
J of Assisted Reproduction and Genetics, Vol 27, no. 9-10, 539-544. Overweight Men: clinical pregnancy after ART is decreased in IVF but not in ICSI cycles. Keltz, et al.