Progesterone:estradiol ratios at implantation in ongoing pregnancies, abortions, and nonconception cycles resulting from ovulation induction

The purpose of this study was to compare progesterone (P):estradiol (E₂) ratios after ovulation induction at the time of implantation in cycles resulting in ongoing pregnancies or abortions and in nonconception cycles. Material included 43 stimulated conception cycles, 29 with human menopausal gonadotropins (hMG) and human chorionic gonadotropins (hCG), 14 with clomiphene citrate (CC) with or without hCG, and 28 nonconception cycles (13 hMG and hCG, 15 CC with or without hCG). Midluteal P and E₂ were measured and expressed in ng/mL. There were no differences in P:E₂ ratios (mean ± SE) for ongoing pregnancies after hMG and hCG (n = 20, 112.6 ± 14.9), CC and hCG (n = 6, 97.0 ± 15.9), or CC alone (n = 5, 96.2 ± 25.5), and the data were pooled . Progesterone:estradiol ratios in 31 ongoing pregnancies and 28 nonception cycles were 107.0 ± 10.7 and 115.2 ± 12.5, respectively, both significantly higher than in 12 abortions (64.5 ± 13.2). In conclusion: (1) P:E₂ ratios at the time of implantation were similar after CC with or without hCG and HMG and hCG treatment; (2) high luteal P:E₂ ratio was associated with ongoing pregnancies; and (3) lower P:E₂ ratio was seen in cycles leading to spontaneous abortions.