Luteal-phase support in stimulated cycles in an in vitro fertilization/embryo transfer program: progesterone versus...

A study was undertaken to compare the hormonal parameters [serum concentrations of estradiol (E2), and progesterone (P) and P/E2 ratios] of patients undergoing in vitro fertilization/embryo transfer to whom either progesterone in oil or human chorionic gonadotropin (hCG) was administered as luteal support. Seventeen patients were studied in 20 cycles. In 10 randomly assigned cycles 25 mg of intramuscular progesterone in oil was administered daily from the day of embryo transfer (day +4) until day +18. In the other 10 cycles, 1500 IU of hCG was given intramuscularly on days +4, +7, +10, and +13. Even when accounting for the differences in recruitment in the two groups, the hCG-treated group had significantly higher concentrations of serum P (P less than 0.01) and E2 (P less than 0.05) during the luteal phase. The luteal P/E2 ratios were higher in the progesterone-treated group because of the lower E2 levels in that group, although the difference was not statistically significant. The ratio of the mean luteal P to the preovulatory serum E2 was significantly higher in the hCG-treated group (P less than 0.01). There were three clinical pregnancies in the hCG-treated group. We conclude that (1) higher P concentrations are achieved with hCG treatment than with progesterone treatment during the luteal phase; (2) high luteal P/E2 ratios per se may not be an important determinant of implantation; (3) progesterone production by the corpus luteum is not maximal in progesterone-treated cycles; and (4) the usefulness of hCG as a luteal support agent should be further evaluated.