Luteal estrogen supplementation in pregnancies associated with low serum estradiol concentrations

The role of luteal phase estrogen in pregnancy outcome has been a matter of considerable debate. In order to evaluate the effectiveness of estrogen supplementation in gonadotropin releasing hormone agonist (GnRHa)/human menopausal gonadotropin (hMG)-stimulated cycles associated with low luteal estrogen concentration, a study was performed comparing the ongoing pregnancy rates in cycles with serum concentrations of estradiol (E2) <100 pg/ml 11 days post embryo transfer (p-ET), treated with luteal phase progesterone (P4) vs. E2 and P4 supplementation. Among 1106 serum samples studied, 951 were from women receiving GnRHa and follicle stimulating hormone (FSH) prior to oocyte retrieval and P4 (50 mg-100 mg IM daily) as luteal phase supplementation beginning day 11 after retrieval. The remaining 155 were from women receiving both E2 (2 mg-6 mg estrace orally each day) and P4 during the luteal phase. Significantly greater frequencies of preclinical losses were observed among women with human chorionic gonadotropin (hCG) concentrations>5 mIU/ml and concurrent E2 concentrations <100 pg/ml compared with E2 >100 pg/ml (p<0.00001). Among the 128 women who had hCG concentrations >5 mIU/ml and E2 concentrations <100 pg/ml, 102 received P4 only during the luteal phase and 26 were treated with estrace 2 mg-6 mg daily, as well as P4 during the luteal phase. The frequency of preclinical pregnancy losses among the 102 women with hCG >5 mIU/ml and E2 <100 pg/ml who did not receive luteal E2 supplementation was 72%, compared with 50% who received luteal E2 supplementation (p=0.04) The increase in preclinical pregnancy loss rates among women not receiving luteal E2 resulted in a decrease in ongoing pregnancy rate (8%), compared to those receiving luteal E2 supplementation (31%) (p=0.002). Our results indicated that a subset of women losing pregnancies preclinically after GnRHa and FSH stimulation due to low luteal phase serum E2 level may benefit from luteal estrogen supplementation. More sensitive and specific markers are needed to identify prospectively women in this risk group.