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.