Amniotic fluid prostanoid concentrations increase early during the course of spontaneous labor at term

Abstract

Objective: The purpose of this study was to determine whether amniotic fluid concentrations of prostanoids increase during spontaneous labor at term.

Study design: Amniotic fluid was retrieved transabdominally from 168 patients in spontaneous labor and from 82 patients not in labor. Prostaglandin E2, prostaglandin F2 alpha, 13, 14-dihydro-15-keto-prostaglandin F2 alpha, thromboxane B2, and 6-keto-prostaglandin F1 alpha concentrations were measured with sensitive and specific radioimmunoassays previously validated for amniotic fluid. Statistical analysis was conducted with Kruskal-Wallis analysis of variance, followed by Dunn's test for multiple comparisons.

Results: (1) Amniotic fluid concentrations of all prostanoids were significantly higher in patients in early labor (cervical dilatation of < or = 3 cm) than in patients not in labor. (2) The magnitude of the increase in amniotic fluid prostanoid concentrations during early labor was significantly greater for prostaglandin F2 alpha and 13,14-dihydro-15-keto-prostaglandin F2 alpha than for prostaglandin E2, thromboxane B2, and 6-keto-prostaglandin F1 alpha. (3) Patients in the active phase of labor with cervical dilatations between 4 and 7 cm did not have higher prostanoid concentrations than those in early labor (cervical dilatation of < or = 3 cm). (4) A significant increase in amniotic fluid concentrations of prostaglandin F2 alpha and 13,14-dihydro-15-keto-prostaglandin F2 alpha was found in patients with advanced cervical dilatation (8 to 10 cm) in comparison with those in early labor (< 3 cm).

Conclusion: Amniotic fluid prostanoid concentrations increase early during the course of spontaneous labor at term.