Impact of clinical and histologic correlates of maternal and fetal inflammatory response on gestational age in preterm births

Objective. To evaluate the impact of clinical and histopathologic correlates related to maternal and fetal inflammatory responses (MIR and FIR) on degree of preterm birth. Methods. Pathology reports and clinical data from 577 singleton preterm births (<37 weeks of gestation) that took place between 1998 and 2004 were analyzed according to decreasing gestational age (≥33 weeks, 29-32 weeks, and <29 weeks). MIR was defined by presence of subchorionitis, chorioamnionitis, deciduitis, or free membranitis; FIR was defined by presence of funisitis or chorionic plate vasculitis. The associations between MIR alone and MIR with FIR and gestational age subgroups were assessed using logistic regression. Results. The presence of FIR in addition to MIR was more strongly associated with degree of prematurity than the presence of MIR alone, especially for those born at <29 weeks (OR = 10.1 (95% CI 4.3-23.7) and OR = 5.3 (95% CI 2.3-12.5), respectively). These associations remained significant after adjusting for maternal race, clinical signs of chorioamnionitis, medically indicated birth, and intrapartum corticosteroid, tocolysis and antibiotic use, and after stratification by clinical signs of chorioamnionitis and medically indicated birth. Conclusions. The combined presence of MIR and FIR is associated with a higher risk of extreme preterm birth (<29 weeks) than MIR alone, suggesting a contributory role of FIR in the pathophysiology of preterm birth.