The impact of maternal body mass index on in vitro fertilization outcomes

To examine the effect of body mass index on gonadotropin dose requirements for ovarian stimulation, as well as other clinical outcomes in women undergoing in vitro fertilization.

We performed a retrospective cohort study involving 752 women undergoing a total of 951 IVF or IVF-ICSI cycles at a private fertility clinic between January 2007 and May 2011. The 951 treatment cycles were divided into three groups according to the weight of the women involved: normal weight (BMI < 25 kg/m², 461 cycles), overweight (25 ≤ BMI < 30 kg/m², 277 cycles), and obese (BMI ≥ 30 kg/m², 179 cycles). Total gonadotropin dose requirements and clinical IVF cycle outcomes (cycle cancellation, clinical pregnancy, and live birth) were compared between the three BMI groups. We performed multivariable analyses, adjusting for potential confounders such as age at cycle start, day 3 serum FSH level, smoking, presence of polycystic ovary syndrome, and duration of infertility.

There were no significant differences between the three BMI groups for any of the IVF cycle outcomes measured, including the total FSH dose required for ovarian stimulation. The likelihood of cycle cancellation, clinical pregnancy, and live birth were not significantly different between normal weight, overweight, and obese women.

Obese women did not require significantly higher doses of gonadotropins for ovarian stimulation than normal weight individuals. At our centre, female obesity did not significantly affect the clinical outcomes of IVF treatment. However, given the conflicting results of existing studies, the effect of maternal obesity on IVF outcomes remains unclear.