Concentrations of progesterone and estradiol (E2) were measured in parturient serum and in fetal cord serum during normal labor and in women with functional dystocia. In the study group, there were no cases of cephalopelvic disproportion. In oxytocin-resistant dystocia, the course of labor could not be corrected with oxytocin. To ascertain the effect of oxytocin, we included a number of women whose labor had been induced with oxytocin, followed by normal cervical dilatation and descent of the fetus. All the parturients were grouped retrospectively into those with normal labor and those with dystocia, based on previous definitions. The serum concentrations of progesterone in both the fetal cord and maternal vein were found to be significantly lower in the oxytocin-resistant dystocia group than in women in spontaneous normal labor and those with oxytocin-induced labor and normal progression (P less than .05-.005). Oxytocin had no evident effect on the serum concentration of either progesterone or E2, nor did concentrations vary following epidural blockade. Serum E2 concentrations in the maternal vein were similar in all delivery groups. Fetal cord E2 serum concentrations were similar in all vaginal deliveries. Women with the most severe oxytocin-resistant dystocia, delivered by cesarean, had significantly lower serum concentrations of E2 in fetal cord serum compared with the vaginally delivered women (P less than .001).