How Obesity Affects Fertility in Women

Over the years numerous articles have confirmed the negative impact of increased body mass index on reproductive outcomes. Studies have shown a 50% reduction in the live birth rates for women with a body mass index of greater than 42 trying to conceive on their own. Similar studies show declining pregnancy rates and increasing miscarriage risk with fertility treatment even with the transfer of healthy embryos. In fact, the impact of high body mass index in a recent analysis showed an average 9% relative increase in the risk of miscarriage for every 5 units of increased BMI.

There has been significant debate as to whether or not this impact was manifested through the uterus or whether it could be affecting the quality of the eggs. In this retrospective study in egg donation, the live birth rate per single embryo transfer showed no significant association with egg donors BMI. However, the recipient’s body mass index had a significant impact on reproduction. The study showed a continuous decrease in live birth rates in women with an increased BMI, and also a continuous increase in miscarriage risk as the recipient BMI increases.

In conclusion, we feel that obesity is a pro inflammatory status and likely contributes to lower pregnancy rates and increased miscarriage risk. We encourage all patients to eat a healthy, balanced diet rich in vegetables and lean protein sources and low in processed carbohydrates and sugars, and to aim for at least 30 minutes of exercise five days a week to help achieve/maintain a healthy weight. Additionally, there is significant promise with some of the newer prescription weight loss drugs which have had a profound impact on weight loss.

Fertility and Sterility® Vol. 121, No. 2, February 2024