['This study was to examine the serum leptin levels in the prediction of pregnancy outcomes in women receiving ovarian hyperstimulation. Effect of leptin on the steroidogenesis was evaluated for granulosa cell (GC) culture in vitro.', 'Serum levels of leptin and estradiol were measured on Day 2, the time of hCG administration and oocyte retrieval in 50 women undergoing long-course GnRH agonist ovarian hyperstimulation. The production of estrogen and progesterone in granulosa cell culture were detected after administration of leptin at the absence or presence of FSH 1 mIU.', 'Leptin levels at the time of hCG injection were significantly lower in the pregnant women than in those without pregnancy. Estradiol concentrations were not correlated with leptin levels during the time of hCG injection and oocyte retrieval. High leptin concentration suppressed both basal estradiol and progesterone productions in GC. Leptin in high doses suppressed estradiol production, but did not alter progesterone production of GC in the presence of FSH.'] Does leptin affect pregnancy outcome of in vitro fertilization and steroidogenesis of human granulosa cells?