Does weight loss in overweight or obese women improve fertility treatment outcomes? A systematic review.

This systematic review assessed the effect of weight loss in overweight and/or obese women undergoing assisted reproductive technology (ART) on their subsequent pregnancy outcome. Weight losses achieved by diet and lifestyle changes, very-low-energy diets, non-surgical medical interventions and bariatric surgery translated into significantly increased pregnancy rates and/or live birth in overweight and/or obese women undergoing ART in 8 of the 11 studies reviewed. In addition, regularization of the menstrual pattern, a decrease in cancellation rates, an increase in the number of embryos available for transfer, a reduction in the number of ART cycles required to achieve pregnancy and a decrease in miscarriage rates were reported. There were also a number of natural conceptions in five of the six studies that reported this outcome. Non-surgical medical weight loss procedures and bariatric surgery induced the greatest weight losses, but their use, as well as that of very-low-energy diets, for weight loss prior to ART requires careful consideration. While the overall quality of the studies included in this review was poor, these results support the clinical recommendation of advising overweight and/or obese women to lose weight prior to ART. Prospective randomized controlled trials are required to establish efficacious evidence-based guidelines for weight loss interventions in overweight and/or obese women prior to ART treatment.