Endocrine changes in the late-follicular and postovulatory intervals as determinants of the in vitro fertilization pregnancy rate.

This investigation examines the hormone pattern in in vitro fertilization (IVF) cycles from the time of human chorionic gonadotropin (hCG) administration through embryo transfer to ascertain whether the absolute levels or secretory patterns of the major reproductive hormones affect the IVF pregnancy rate. Thirty-one women who underwent IVF treatment were enrolled in the study. All patients received clomiphene citrate/human menopausal gonadotropin for ovulation induction. Significant elevations in serum estradiol (E2) levels in the pregnant group were found throughout the cycle interval studied. After hCG administration the serum hCG levels were not different between the groups. Significant elevations in serum progesterone (P) concentrations were found in the pregnant group from the day after laparoscopy through embryo transfer. Embryos obtained from the pregnant group appeared to be different in that the mean number of blastomeres per embryo transferred was significantly greater. Therefore for achievement of an IVF pregnancy the optimal hormone pattern employing combination ovulation induction in the ovulation to transfer interval is a relatively high E2 level in ovulation followed by a high P level at transfer and into the luteal phase. These elevated hormone levels do not depend on the response to exogenous hCG.