Background:It is not possible to identify the cause of the recurrent early pregnancy loss in approximately half of the cases, and different results have been reported according to estrogen (ER) and progesterone receptors (PR). The objective of this work was to evaluate the PR and ER levels in the endometrium of patients with recurrent early pregnancy loss, and to compare them with those of patients with proven fertility.
Material/Methods:Endometrial receptors (R) for estrogen and progesterone as well as estradiol (E2,) and progesterone (P) levels were determined in patients with recurrent early pregnancy loss, and compared with patients with proven fertility.
Results:The E2 and P levels, and the E2/P ratio did not show significant differences among the groups. Estrogen receptor in the cytoplasm and nucleus was lower in those with miscarriages, but without significant differences between the groups. However, the cytoplasmic PR was lower in those with pregnancy loss (p<0.04), while nuclear PR was lower in the control group (p<0.04).
Conclusions: Maybe low PR levels can be the cause of early pregnancy loss of unknown etiology, but this deserves further investigation.

Keywords: Endometrium, early pregnancy, abortion, Progesterone, estrogen, receptors