Sex steroid receptors and human parturition

To investigate the correlation between sex steroid hormones and their receptors during normal and dysfunctional labor.

Myometrial and decidual biopsies along with maternal and cord blood samples were taken from women with or without labor activity. Estrogen and progesterone receptor contents in myometrium and decidua were determined by enzyme immunoassay, and hormone concentrations were analyzed by radioimmunoassay.

In the lower segment of the uterus, the progesterone receptor concentrations of myometrium were significantly lower in oxytocin-resistant dystocia compared with those of normal labor and before labor (P < .04, P < .005, respectively). No significant difference was found in the estrogen receptors contents in the groups studied. The progesterone receptors of myometrium from the upper segment showed higher concentrations in active labor compared with those before labor and oxytocin-resistant labor (P <.01, P < .05, respectively). Estrogen receptors from the upper segment showed no significant difference in these regards. There was no difference in peripheral and myometrial sex hormone levels in the groups studied.

These data suggest that, in the human, 1) oxytocin-resistant labor is associated with low levels of progesterone receptors, 2) estrogen receptors content in myometrium might have no or little relation to labor, and 3) functional labor seems not to be related to a decreased progesterone activity in the myometrium.