The Effect of Obesity on Assisted Reproduction- Emerging Trends

As obesity becomes more prevalent across all demographics in the United States and worldwide, it exerts an effect on other health conditions. Research presented at the 67th Annual Meeting of the American Society for Reproductive Medicine (ASRM) provides an overview of the impact of excessive body weight on assisted reproduction.
In a retrospective study, doctors reviewed all fresh ART cycles conducted at Walter Reed Army Medical Center between January 2002 and 2010 and evaluated certain outcomes by patients’ body mass index (BMI). In 1,625 cycles, they found no significant differences between the different BMI groups (underweight, normal weight, overweight, obese, morbidly obese) in the number of eggs retrieved, the percentages of mature eggs retrieved, or the percentage of women who became pregnant. Pregnancy was determined by serum HCG levels.
In another retrospective study, researchers at Beth Israel Deaconess Medical Center/Boston IVF evaluated data from 4,609 patients with documented BMI undergoing their first IVF cycle using their own eggs. After controlling for maternal and paternal age and other factors, the odds of obese patients (BMI 30 to 39.99) having a live birth were 30-61% lower than for normal weight patients and the odds of morbidly obese patients (BMI 40 and over) having a live birth were 68% lower than those for normal weight patients. The chances of obese and morbidly obese patients achieving a clinical pregnancy were also lower in this study.
A meta-analysis of controlled studies conducted by Egyptian researchers showed that obese women undergoing IVF and ICSI have significantly lower live birth and clinical pregnancy rates in addition to significantly higher cycle cancellation rates and miscarriage rates.
There is not a consistent trend connecting BMI with successful outcomes in embryo donation. At the National Embryo Donation Center (NEDC) in Knoxville, TN, a study was devised to compare the relationship of BMI to clinical pregnancy rates in patients undergoing transfer of donated embryos. Clinical pregnancy rates were calculated for 305 patients receiving donor embryo transfer between 2004 and 2009. The patients were grouped into the different BMI categories and their pregnancy rates were compared to the corresponding pregnancy rates of IVF and egg donation in a data analysis published by the Society for Assisted Reproductive Technology (SART). The SART data showed that women with BMIs in the obese ranges were less likely to achieve a clinical pregnancy using their own eggs and about as likely as normal weight women to become pregnant using donor eggs. For donated embryo cycles, the NEDC data showed no consistent relationship between recipient BMI and the likelihood of a clinical pregnancy.
Marcelle Cedars, MD, President of the Society for Reproductive Endocrinology and Infertility, commented, “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 and embryo development, the uterine environment or other mechanisms of reproductive physiology, it is clear that ART patients fare better if they are not obese.”