Leptin is involved not only in the regulation of food intake but also in other functions including reproduction. Because leptin has been demonstrated to influence ovarian steroidogenesis directly and leptin levels vary during the menstrual cycle and in stimulated cycles, we tested the hypothesis that serum or intrafollicular concentrations of leptin would correlate with reproductive outcomes in intracytoplasmic sperm injection cycles. Serum and follicular fluid samples were collected from 77 women undergoing ovarian stimulation, intracytoplasmic sperm injection and embryo transfer due to male factor infertility. The concentrations of total leptin, both in serum and in pooled follicular fluid samples, did not correlate with the number of oocytes, the fertilization rate or the embryo quality. Additionally, leptin concentrations did not differ between cycles that resulted in pregnancy and those that failed. These results raise objections to the prognostic value of leptin for the outcome of in vitro fertilization/intracytoplasmic sperm injection cycles
