Does obesity have detrimental effects on IVF treatment outcomes?

BACKGROUND The aim of this study was to investigate the influence of body mass index (BMI) on the in vitro fertilization (IVF) treatment outcomes in a cohort of women undergoing their first IVF, using an intracytoplasmic sperm injection (ICSI). METHODS This retrospective cohort study included 298 cycles from women younger than 38 years old undergoing IVF-ICSI at a university infertility clinic. The treatment cycles were divided into three groups according to the BMI of the women involved: normal weight (18.5 ≤ BMI < 25 kg/m(2), 164 cycles), overweight (25 ≤ BMI < 30 kg/m(2), 70 cycles), and obese (BMI ≥ 30 kg/m(2), 64 cycles). The underweight women (BMI < 18.5 kg/m(2)) were not included in the analysis due to small sample size (n = 22). The patient characteristics and IVF-ICSI treatment outcomes were compared between the BMI groups. RESULTS The total gonadotropin dose (p <0.001) and duration of stimulation (p = 0.008) were significantly higher in the obese group when compared to the normal BMI group. There were no significant differences across the BMI categories for the other IVF-ICSI cycle outcomes measured, including the number of retrieved oocytes, mature oocytes, embryos suitable for transfer, proportion of oocytes fertilized, and cycle cancellation rates (p >0.05 for each). Additionally, clinical pregnancy, spontaneous abortion, and the ongoing pregnancy rates per transfer were found to be comparable between the normal weight, overweight, and obese women (p >0.05 for each). CONCLUSION Obese women might require a significantly higher dose of gonadotropins and longer stimulation durations, without greatly affecting the pregnancy outcomes.