Chorioamnionitis without foetal inflammatory response is associated with stillbirth in early preterm pregnancies.

Objective: The aim of this study was to compare placental findings from early preterm stillbirths with gestational week-matched liveborn infants. The main focus was to investigate the differences in the presence and distribution of inflammatory signs in the placentas of these two groups, especially referring to histological acute chorioamnionitis (CAM). Methods: A case-control study of preterm stillbirths, between 22 and 32 weeks gestation, here referred to as early preterm, (cases, n = 112) and gestational week-matched liveborn infants (references, n = 166) in Stockholm. Relevant clinical data were collected from a web-based database (for cases) and delivery records (for references). Macroscopic and histological examinations of placentas were performed according to a structured protocol (placental weight relative to gestational age, accelerated villous maturation, infarction, intervillous thrombosis, foetal thrombosis, chronic villitis and CAM (polymorphonuclear leucocytes in the chorion/amnion), with and without foetal inflammatory responses (FIRs) (vasculitis in placental and/or cord vessels and funisitis). Statistical analyses were performed using a multivariable logistic regression. Results: Small for gestational age (AOR: 2.13, CI: 1.26-3.62) and CAM without a FIR (AOR: 2.44, CI: 1.10-5.41) were associated with an elevated risk of preterm stillbirth. Conclusions: Histological acute CAM without a FIR is associated with a higher risk for stillbirth in early preterm pregnancies. [ABSTRACT FROM AUTHOR]