Egg Donor Recipients: Think Your Weight Doesn’t Matter? Think Again!

Recently there was a paper in the journal Fertility and Sterility (Fertil Steril 2013;100:1050–8) about a study that was done in Spain with egg donors and egg donor recipients to see if the body mass index (BMI) of the recipient was relevant to the outcome of the cycle. This study involved 9,587 recipient women.

Bellver et al. divided these women into four groups based off their BMI. The first group of women had a BMI of less than 20 (lean), the second group had BMI of 20-24.9 (normoweight), the third group’s BMI was 25-29.9 (overweight), and the fourth group was women with a BMI of 30 or greater (obese). All of these women had the same protocol to get their lining ready for an embryo transfer. There was not a great variance in age between the four groups; it was only 12 months.

The group of egg donors was then also split into four groups. Because egg donors have to fit a strict parameter of requirements to qualify to be an egg donor, the variance in age and BMI was negligible. This program required that their donors have a BMI of less than 25. They all had similar ages, BMI, and stimulation protocols. All four groups were considered equal.

This study was not looking for pregnancy rates; they were in search of the live birth rate for these women. They wanted to know that not only did the recipient achieve a pregnancy; they wanted to make sure that she carried her pregnancy and delivered a baby at the end and they wanted to see which group of women had the highest live birth rate.

The result of this study showed that recipients with lower BMI had both a higher positive pregnancy test, clinical pregnancy, AND a higher live birth rate. This is important to the field of fertility because based off this information we now know that having a higher BMI does affect a woman’s uterine receptivity. Lowering your BMI, even a little bit, can only help your cycle, whether you are doing IUI, IVF, or IVF with an egg donor.