Influence of progesterone/estradiol ratio on luteal function for achieving pregnancy in gonadotropin therapy

The purpose of this study was to evaluate the influence of the relationship between plasma progesterone (P4) and estradiol (E2) levels in the luteal phase for achieving pregnancy in human menopausal gonadotropin (hMG)-human chorionic gonadotropin (hCG)-treated cycles. Plasma P4 and E2 levels were determined in 93 hMG-hCG-treated cycles (23 pregnant and 70 nonpregnant) of 46 patients during 3 periods of the luteal phase, using radioimmunoassay. In addition, 88 spontaneous ovulatory cycles and 100 clomiphene-treated cycles were also studied in the same manner. In hMG-hCG-treated cycles in the early luteal phase, the P4/E2 ratio in pregnant cycles was significantly higher than that in nonpregnant cycles. There was no significant difference between the P4/E2 ratios of the luteal phase of hMG-hCG-treated pregnant-group, clomiphene-treated and spontaneous ovulatory cycles. In nonpregnant cycles, however, the P4/E2 ratio in hMG-hCG-treated cycles was significantly lower than that in clomiphene-treated or spontaneous ovulatory cycles. These results suggest that in hMG-hCG-treated cycles, the P4/E2 ratio may be a more reliable index of luteal function for achieving pregnancy than P4 levels alone.