Histologic Chorioamnionitis in Pregnancies Complicated by Preeclampsia and the Effect on Neonatal Outcomes.

Histological chorioamnionitis (HC) is a common placental finding that represents acute/chronic inflammation and can affect neonatal outcomes. We aimed to examine the effect of HC on neonatal outcomes in pregnancies complicated by preeclampsia. All pregnancies with the diagnosis of preeclampsia at 24-42 weeks between 2008 and 2019 were reviewed. Placental lesions were classified according to the "Amsterdam" criteria. Composite adverse neonatal outcome included ≥1 early complication. Maternal and neonatal outcomes were compared between cases with and without HC. Multivariable regression analysis was performed to identify independent associations with adverse neonatal outcome. Compared to preeclampsia without HC (n=517), preeclampsia with HC (n=55) was characterized by a more advanced gestational age (p<0.001) and a higher rate of nulliparity (p=0.02). Diabetes was more prevalent in preeclampsia without HC (p=0.039) as was a history of previous preeclampsia (p=0.048). Neonates in the preeclampsia with HC group had higher rates of adverse neonatal outcome (p<0.001) and Apgar scores <7 at 5 min (p=0.034) despite a higher birthweight (p=0.005). Preeclampsia without HC was associated with smaller placentas and a higher rate of placental maternal vascular malperfusion lesions (p=0.014 and p<0.001 respectively). By multivariate analysis, gestational age and HC were independently associated with adverse neonatal outcome (aOR 0.88 95% CI 0.76-0.96, and aOR 1.33, 95% CI 1.11-3.09, respectively). In preeclampsia, concomitant HC was associated with adverse neonatal outcome despite a more advanced gestational age and higher neonatal birthweight. This inflammatory mechanism probably plays a role in a more severe subgroup of preeclampsia cases, causing an additional risk for the developing fetus.