Nelson SM, Fleming RF.
Hum Reprod. 2007 Apr;22(4):912-5. Epub 2006 Dec 15.  

Obesity is a major health problem across the world. Recent editorials suggest that obese patients should be denied treatment of any kind aimed to improve ovulation rates and achieve pregnancy until they have reduced their BMI. We propose that this approach is not a resolution of the problem, but indeed may amplify the maternal and perinatal complications attributed to fertility centers.

Obesity independent of polycystic ovary syndrome (PCOS) is associated with anovulation, and minimal weight loss alone is an effective therapy for induction of ovulation in both obese women and obese PCOS women. Consequently, lifestyle programmes encouraging weight loss should be considered to be an ovulation induction therapy and due consideration for a potential pregnancy in an obese woman given.

We propose that women with a BMI in excess of 35 kg m(2) should lose weight prior to conception-not prior to receiving infertility treatment. Therefore, clinicians undertaking the management of infertility in obese women should adopt measures to reduce their body mass prior to exposing them to the risks of pregnancy.

We advocate that this approach should be aggressively managed including pharmacological strategies; intrinsic in this programme is the use of contraception and high-dose folic acid during that period of conceptual weight reduction.