Placental pathologic aberrations in cases of familial idiopathic spontaneous preterm birth

Objective: To test the hypothesis that placental histologic characteristics in familial spontaneous preterm birth (sPTB) differ by gestational age (GA) and reflect possible mechanisms of pathogenesis.

Study design: Secondary analysis from prospective cohort study in women with sPTB <35 weeks and a first degree family member with PTB. Placental specimens (n = 79) were categorized by maternal and/or fetal inflammatory response (MIR, FIR) and compared among three preterm GA categories.

Results: Inflammatory changes were common. MIR was most frequent at the earliest GAs, 85% with PTB <28 weeks [(adj)OR 77.5 (95% CI 5, 1213.1)], and 57% at 28-32 weeks [(adj)OR 6.1 (0.8, 48.5)] compared to later PTBs occurring at 32-35 weeks (22%). FIR also occurred most frequently in the earliest cases of PTB <28 weeks.

Conclusions: Placental inflammatory responses are common in women with familial sPTB. This data suggests that inflammation plays an important role in the onset of parturition in cases otherwise classified as idiopathic or spontaneous in nature, especially at the earliest GAs when neonatal outcomes are the poorest.