The amniotic fluid prostaglandin F2α concentration in patients with preterm labor

Abstract

Objective: To determine if an elevated amniotic fluid concentration of prostaglandin F2α (PGF2α) is associated with intra-amniotic inflammation/infection and adverse pregnancy outcomes in patients with preterm labor and intact membranes. Methods: A retrospective cohort study was performed including 132 singleton pregnancies with preterm labor and intact membranes (<35 weeks). Amniotic fluid was cultured for aerobic and anaerobic bacteria as well as genital mycoplasmas. Intra-amniotic inflammation was defined as an elevated amniotic fluid matrix metalloproteinase-8 (MMP-8) concentration (>23 ng/mL). PGF2α was measured with a sensitive and specific immunoassay. The amniotic fluid PGF2α concentration was considered elevated when it was above the 95th percentile for amniotic fluid PGF2α concentrations among pregnant women at 15-36 weeks of gestation who were not in labor (≥170 pg/mL). Results: (1) The prevalence of an elevated amniotic fluid PGF2α concentration was 40% (53/132) in patients with preterm labor and intact membranes

(2) patients with an elevated amniotic fluid PGF2α concentration had significantly higher rates of a positive amniotic fluid culture [19% (10/53) vs. 5% (4/79)

p=0.019], intra-amniotic inflammation/infection [49% (26/53) vs. 20% (16/79)

p=0.001], spontaneous preterm delivery, clinical and histologic chorioamnionitis as well as funisitis, higher median amniotic fluid MMP-8 concentration and amniotic fluid white blood cell count, and shorter amniocentesis-to-delivery interval than those without an elevated amniotic fluid PGF2α (p<0.05 for each)

and (3) an elevated amniotic fluid PGF2α concentration was associated with a shorter amniocentesis-to-delivery interval after adjustment for the presence of intra-amniotic inflammation/infection [hazard ratio 2.1, 95% confidence interval (CI) 1.4-3.1

p=0.001]. Conclusions: The concentration of PGF2α was elevated in the amniotic fluid of 40% of patients with preterm labor and intact membranes and is an independent risk factor for intra-amniotic inflammation/infection, impending preterm delivery, chorioamnionitis and funisitis.