Ovarian stimulation in women with high and normal body mass index: GnRH agonist versus GnRH antagonist

In modern society, obesity has become a major health problem and has been associated with impaired fertility. The aim of this study is to assess the role of obesity in women undergoing controlled ovarian hyperstimulation (COH) stimulated either with GnRH agonists or with GnRH antagonists. Records of 463 women undergoing in vitro fertilization (IVF) treatment were reviewed. The influence of body mass index (BMI) on treatment outcome was examined, after accounting for differences in stimulation protocols. In the agonist group (286 patients), the total amount of gonadotropins used was significantly higher in patients with a BMI >= 25 kg/m(2), when compared to those with a normal BMI. The same result was found in the antagonist group (177 patients). No significant differences were found in length of stimulation, number of oocytes retrieved or number of embryos transferred. In both the antagonist and the agonist group, the number of clinical pregnancies was found to be higher in patients with normal BMI, suggesting that obesity could impair the ovarian response to exogenous gonadotropins. Considering the results obtained and the many theoretical advantages of GnRH antagonists, ovarian stimulation with GnRH antagonists is an efficient treatment for both women with normal and high BMI.