AMNIOTIC-FLUID PROSTANOID CONCENTRATIONS INCREASE EARLY DURING THE COURSE OF SPONTANEOUS LABOR AT TERM

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 lab or. Prostaglandin E(2), prostaglandin F-2 alpha, 13, 14-dihydro-15-ket o-prostaglandin F-2 alpha, thromboxane B-2, and 6-keto-prostaglandin F -1 alpha concentrations were measured with sensitive and specific radi oimmunoassays previously validated for amniotic fluid. Statistical ana lysis 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 patient s in early labor (cervical dilatation of less than or equal to 3 cm) t han in patients not in labor. (2) The magnitude of the increase in amn iotic fluid prostanoid concentrations during early labor was significa ntly greater for prostaglandin F-2 alpha and 13, 14 dihydro-15-keto-pr ostaglandin F-2 alpha than for prostaglandin E(2), thromboxane B-2, an d 6-keto-prostaglandin F-1 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 dilatat ion of less than or equal to 3 cm). (4) A significant increase in amni otic fluid concentrations of prostaglandin F2 alpha and 13,14-dihydro- 15-keto-prostaglandin F-2 alpha, was found in patients with advanced c ervical dilatation (8 to 10 cm) in comparison with those in early labo r (<3 cm). CONCLUSION: Amniotic fluid prostanoid concentrations increa se early during the course of spontaneous labor at term.