Body mass index is inversely related to intrafollicular HCG concentrations, embryo quality and IVF outcome.

Decreased periovulatory human chorionic gonadotrophin (HCG) concentrations have been shown to be associated with diminished fertilization rates. This study evaluated if intra-follicular HCG concentration may be related to body mass in 247 IVF patients using their own oocytes and 58 patients receiving donor oocytes, and evaluated if such a relationship might affect IVF outcome. A significant inverse correlation (r = -0.353, P < 0.001) was observed between the body mass index (BMI) and intra-follicular HCG concentration. The mean HCG concentrations were significantly decreased (P < 0.001) in patients with a BMI >30 kg/m(2) compared with patients with a BMI of 20-30 kg/m(2) or BMI <20 kg/m(2) (17.6 versus 45.1 and 52.5%, respectively). The clinical pregnancy rates (P < 0.001) and embryo quality (P < 0.05) were significantly different for the three groups. In donor oocyte recipients, the pregnancy rate was significantly decreased (P < 0.0001) for recipients with a BMI >25 kg/m(2) compared with those with a BMI from 21-25 kg/m(2) and BMI <21 kg/m(2) (43.8 versus 72 and 76.5%, respectively). These data indicate that intra-follicular HCG concentration is inversely related to BMI, and may be related to a concurrent decrease in embryo quality and pregnancy rates.