[Estrogen and progesterone levels in serum and amniotic fluid before or during term labor and their relationship to uterine activity].

Estradiol (E2), estriol (E3) and progesterone (P) were measured in the serum and amniotic fluid by radioimmunoassay in 73 cases, both before or during term labor. The results showed: (1) the serum E2, E3, P, E2/P and Es/P values did not differ significantly between the two groups; (2) the amniotic fluid E2 and E3 concentrations were significantly higher for women in active labor and more evident in those with normal uterine activity, but the progesterone concentration did not vary significantly among the three groups. Thus, the increase of estrogen and estrogen/progesterone ratio in amniotic fluid may be related to the mechanism of spontaneous onset of term parturition in human and as well to dysfunctional labor.