Impact of High BMI on Assisted Reproductive Outcomes Unclear

Megan Brooks

November 03, 2011

November 3, 2011 (Orlando, Florida) — The impact of obesity on the outcome of assisted reproduction remains unclear, according to research presented here at the American Society for Reproductive Medicine 67th Annual Meeting.

In one study, James Segars, MD, from the Walter Reed IVF Center, in Washington, DC, and colleagues looked back at all women who underwent fresh assisted reproductive technology cycles at the Walter Reed Army Medical Center from January 2002 to 2010. All of them underwent controlled ovarian stimulation with either luteal lupron or microdose lupron protocols.

The researchers grouped the patients into 5 categories by body mass index (BMI): below 18.6 kg/m2 (underweight), 18.6 to 24.9 kg/m2 (normal weight), 25.0 to 29.9 kg/m2 (overweight), 30.0 to 39.9 kg/m2 (obese), and above 40 kg/m2 (morbidly obese).

In 1625 cycles, the researchers found no significant differences among the different BMI groups in the number of oocytes retrieved, the percentage of mature oocytes retrieved, or the percentage of women who became pregnant (determined by serum human chorionic gonadotropin levels).

Table 1: Assisted Reproductive Technology Outcomes by Weight Group

Weight Group Oocytes Retrieved (n) % Mature Pregnancy (%)
Underweight 16 66 55
Normal 16 74 52
Overweight 15 71 51
Obese 16 73 51
Morbidly obese 15 74 57

In another study, however, researchers at Beth Israel Deaconess Medical Center/Boston IVF, in Massachusetts, found evidence that obese women have up to 68% lower odds of having a live birth after in vitro fertilization (IVF), even after controlling for confounding variables.

David Ryley, MD, and colleagues evaluated data from 4609 patients who had their first autologous IVF cycle from 2004 to 2010. After controlling for maternal and paternal age and other factors, women who were overweight or obese had lower odds of having a clinical pregnancy and live birth than their normal-weight peers.

Table 2: IVF Outcomes by Weight Group (95% Confidence Interval)

Weight Group Clinical Pregnancies Live Births
Normal 0.90 (0.74–1.09) 0.96 (0.78–1.18)
Overweight 0.70 ( 0.53–0.92) 0.63 (0.47–0.85)
Obese 0.41 (0.27–0.62) 0.39 (0.25–0.61)
Morbidly obese 0.43 (0.24–0.76) 0.32 (0.16–0.64)

A third presentation, a meta-analysis of 10 relevant studies conducted by researchers from Egypt, supports the Boston study. It suggests that obese women undergoing IVF and intracytoplasmic sperm injection have significantly lower live birth and clinical pregnancy rates, in addition to significantly higher cycle cancellation rates and miscarriage rates.

In a statement from the conference, Marcelle Cedars, MD, president of the Society for Reproductive Endocrinology and Infertility, said: "Most studies show that live birth rates and certain other measurements of IVF outcomes are significantly poorer in obese patients."

"Whether future research reveals that excess weight acts on egg quality, embryo development, the uterine environment, or other mechanisms of reproductive physiology, it is clear that [assisted reproduction] patients fare better if they are not obese," she explained.

The authors have disclosed no relevant financial relationships.

American Society for Reproductive Medicine (ASRM) 67th Annual Meeting: Abstracts 276, 277, 278. Presented October 19, 2011.


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