The late luteal phase in infertile women: comparison of simultaneous endometrial biopsy and progesterone levels.

Endometrial biopsy specimens were obtained from 107 normally menstruating infertile women 2 to 3 days before the anticipated onset of menses and were day-dated according to histologic criteria. A simultaneous blood sample was obtained for measurement of progesterone (P) and beta-subunit of human chorionic gonadotropin. Of 98 biopsies which could be accurately dated, 56 were in-phase (IP) and 42 were out-of-phase (OOP). Mean serum P levels were significantly lower in women with OOP biopsies undertaken more than 4 days before the onset of menses. A sharp decline in serum P levels was observed in women with IP but not OOP biopsies, so that on the final premenstrual day serum P levels were significantly higher than normal in women with OOP biopsies. Pregnancy continued without interruption in two of six patients who underwent biopsy in the cycle of conception. One patient had an ectopic pregnancy; and the three remaining pregnant patients, all with subnormal P values, aborted. The study suggests that there is a high frequency of minor abnormalities in luteal function in normally menstruating, infertile women for whom tubal and male factors were normal. The frequency of subclinical pregnancy (2 of 107) was lower than anticipated from earlier studies.