Serum progesterone and oestradiol concentrations in women with unexplained infertility.

Twenty-eight patients with longstanding, unexplained infertility were studied during one menstrual cycle by serial serum progesterone and oestradiol assays. For comparison the serum concentrations of these hormones were also measured during one cycle in ten fertile control subjects. Of the patients with infertility, one had an anovulatory cycle and one had a cycle with a short luteal phase. In the other 26 patients the length of the cycle, the preovulatory peak oestradiol concentration and the maximum oestradiol concentration during the luteal phase were less than in the controls but these differences were not statistically significant (p > 0.10). However, the duration of progesterone secretion and the maximum progesterone concentration during the luteal phase were significantly less (p < 0.01) in the patients with infertility than in the controls. It is, however, uncertain whether the subnormal progesterone secretion is responsible for the infertility.