The Association between Intrauterine Inflammation and Spontaneous Vaginal Delivery at Term: A Cross-Sectional Study

Michiel L Houben,Maroeska M Rovers,Leontine Schuijff,Jan L L Kimpen,Wouter J De Waal,Annemiek Evers,Grada M Van Bleek,Gerard H A Visser,Hilda Kessel,Peter G J Nikkels,Louis Bont,Linda Wright

doi:10.1371/journal.pone.0006572

Abstract

BackgroundDifferent factors contribute to the onset of labor at term. In animal models onset of labor is characterized by an inflammatory response. The role of intrauterine inflammation, although implicated in preterm birth, is not yet established in human term labor. We hypothesized that intrauterine inflammation at term is associated with spontaneous onset of labor.Methods/ResultsIn two large urban hospitals in the Netherlands, a cross-sectional study of spontaneous onset term vaginal deliveries and elective caesarean sections (CS), without signs of labor, was carried out. Placentas and amniotic fluid samples were collected during labor and/or at delivery. Histological signs of placenta inflammation were determined. Amniotic fluid proinflammatory cytokine concentrations were measured using ELISA. A total of 375 women were included. In term vaginal deliveries, more signs of intrauterine inflammation were found than in elective CS: the prevalence of chorioamnionitis was higher (18 vs 4%, p = 0.02) and amniotic fluid concentration of IL-6 was higher (3.1 vs 0.37 ng/mL, p<0.001). Similar results were obtained for IL-8 (10.93 vs 0.96 ng/mL, p<0.001) and percentage of detectable TNF-α (50 vs 4%, p<0.001).ConclusionsThis large cross-sectional study shows that spontaneous term delivery is characterized by histopathological signs of placenta inflammation and increased amniotic fluid proinflammatory cytokines.

Highlights

Normal human delivery is initiated by the spontaneous onset of labor at term.[1]
This large cross-sectional study shows that spontaneous term delivery is characterized by histopathological signs of placenta inflammation and increased amniotic fluid proinflammatory cytokines
Informed consent was obtained from 375 mothers.(figure 1) Clinical characteristics of the excluded mothers and their children were similar to the characteristics of those included

Summary

Introduction

Normal human delivery is initiated by the spontaneous onset of labor at term.[1] The role of inflammation in the onset of labor at term in humans is poorly understood, it has been implicated in the physiological onset of parturition.[2,3,4,5] Inflammation at term comprises the gold standard of histologically proven infiltration of the chorioamniotic tissue, and presence of inflammatory mediators in the amniotic fluid.[6] Microbial invasion of the amniotic space is found in up to 19% of term pregnancies.[7] infection contributes only to a small proportion of cases with signs of chorioamnionitis; amniotic fluid appears sterile in the majority of these cases. The role of intrauterine inflammation, implicated in preterm birth, is not yet established in human term labor. We hypothesized that intrauterine inflammation at term is associated with spontaneous onset of labor

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