Effect of body mass index on IVF treatment outcome: an updated systematic review and meta-analysis

There is conflicting evidence regarding the effect of raised body mass index (BMI) on the outcome of assisted reproductive technology. In particular, there is insufficient evidence to describe the effect of BMI on live birth rates. We carried out a systematic review and meta-analysis of studies to evaluate the effect of raised BMI on treatment outcome following IVF/ICSI treatment. Subgroup analysis on overweight and obese patients was performed. Literature searches were conducted on MEDLINE, EMBASE and the Web of Science from 1966 to 2010. Thirty-three studies including 47,967 treatment cycles were included. Results indicated that women who were overweight or obese (BMI ≥ 25) had significantly lower clinical pregnancy (RR=0.90, P<0.0001) and live birth rates (RR=0.84, P=0.0002) and significantly higher miscarriage rate (RR=1.31, P < 0.0001) compared to women with a BMI < 25 following treatment. A subgroup analysis of overweight women (BMI ≥ 25-29.9) revealed lower clinical pregnancy (RR=0.91, P=0.0003) and live birth rates (RR=0.91, P=0.01) and higher miscarriage rate (RR=1.24, P < 0.00001) compared to women with normal weight (BMI < 25). In conclusion, raised BMI is associated with adverse pregnancy outcome in women undergoing IVF/ICSI treatment, including lower live birth rates. This effect is present in overweight as well as obese women.