High BMI Tied to Worse Fertility Treatment Outcomes

Higher BMI may lower the success rate of fertility treatments, according to three studies presented at the American Society for Reproductive Medicine (ASRM) 2014 Annual Meeting.

Often, eggs from one donor are provided to a number of different recipients who are undergoing fertility treatment. To evaluate the effect of recipient BMI on live birth, researchers examined outcomes among different women who received oocytes from the same donor.

Using data from fresh, shared donor cycles performed from 2004 to 2012, the researchers examined cases where one donor’s eggs were given to different women with varying BMIs.

Of the 3,922 cycles identified, 63% of recipients had a BMI less than 25, 24% had a BMI between 25 and 30, and 8% had a BMI between 30 and 35, according to the data.

Results linked increasing BMI with a lower live birth rate, even after adjustment for age, number of embryos transferred, embryo stage, embryo grade and presence of severe male factor (relative risk [RR]=0.990; 95% CI, 0.981-0.998).

The association appeared to be strongest in those recipients with a BMI greater than 35, who had a 21% lower live birth rate (RR=0.790; 95% CI, 0.626-0.977), compared with normal-weight recipients, the researchers reported.

However, they did not observe significant differences in recipients with BMIs between 25 and 30 (RR=0.958; 95% CI, 0.872-1.053) or those with BMIs between 30 and 35 (RR=0.931; 95% CI, 0.807-1.072).

“This large dataset suggests a benefit to counseling on weight modification in obese recipients, with the greatest potential benefit for recipients with morbid obesity,” the researchers wrote in an abstract.

In keeping with these findings, a second study showed that success rates in egg donor cycles are more favorable in recipients with low and normal BMI.

For this study, the researchers analyzed data from 2008 to 2010 from the SART registry. They found that the live birth rate was more than 50% in recipients with a BMI less than 25 vs. 40% in those with a BMI between 40 and 45.

These researchers also conducted another study in which they assessed the association between live birth rate and BMI in women who underwent in vitro fertilization (IVF) cycles using their own eggs. Again, they used data on 239,127 fresh cycles from the SART registry from 2008 to 2010.

In these cycles using the patient’s own eggs, live birth rate ranged from 31% in women with a BMI less than 25 to 21% for those with a BMI of greater than 50, the researchers noted.

“We have known that there was a relationship between BMI and the outcomes of fertility treatment. These studies examining outcomes from women using their own eggs, from donor eggs and even eggs from one donor going to different recipients allow us to further develop our understanding of the importance of BMI. It is clear; lower BMIs are associated with greater likelihood of success for infertility patients,” Rebecca Z. Sokol, MD, MPH, president of ASRM, said in a press release.

References

1. Zarek SM et al. Abstract O-8.
2. Provost MP et al. Abstract O-47.
3. Provost MP et al. Abstract O-49. All presented at: American Society for Reproductive Medicine (ASRM) 2014 Annual Meeting; Oct. 18-22, 2014; Honolulu.