Endometrial dating in the conception cycle

To investigate endometrial dating during the conception cycle.

Endometrial biopsies of the last half of the luteal phase of conception cycles were dated based on urinary luteinizing hormone (LH) surges.

Endometrial samples were obtained from women attending the fertility clinic of the Department of Obstetrics and Gynecology at Gunma University Hospital.

One hundred eighty-five women, of whom 15 (8.1%) conceived during this study.

Urinary LH surge, serum progesterone (P) levels, and endometrial dating.

All 10 women who conceived showed 2 or within 2 days in-phase endometrial biopsies on days 7 to 11 after the LH surge. In 4 of 5 women biopsied on day 12, an unequivocally delay in the stroma was found, i.e., a persistence of edema and poor development of predecidual reaction. Since serum P levels in conception cycles were significantly higher than in nonconception cycles on days 10, 11, and 12, we interpreted this delay in the stroma as a consequence of conception.

Endometrial specimens during the last half of the luteal phase of conception cycles are in-phase until day 12. On day 12, gestational hyperplasia causes apparent out-of-phase.