Unraveling the role of parity in placentas from antepartum stillbirth.

OBJECTIVE: Placental pathology is a leading contributor to stillbirth; however, whether placental histopathological lesions differ according to parity in stillbirth remains poorly defined. The aim of the present study is to evaluate the association between parity and placental histopathological lesions in singleton pregnancies ending in antepartum stillbirth. STUDY DESIGN: Retrospective review of placentas from singleton antepartum stillbirths, in non-macerated and morphologically normal fetuses, was performed blinded to clinical data. Placental lesions were classified per international consensus criteria and compared between nulliparous and parous women. RESULTS: Placental histopathological abnormalities were identified in the vast majority of cases in both nulliparous and parous women (>94%). The prevalence of maternal vascular malperfusion, fetal vascular malperfusion, delayed villous maturation, and ascending intrauterine infection did not differ between groups. In contrast, villitis of unknown etiology (VUE) was significantly more frequent in parous than in nulliparous women (13.2% vs. 1.6%). All VUE cases represented high-grade lesions, and were frequently associated with low birth weight. CONCLUSIONS: Among placental lesions in stillbirth, high-grade VUE shows an association with parity. Systematic placental histopathology evaluation may enhance the etiological classification of stillbirth, providing potential mechanistic insights. This knowledge can support more accurate recurrence risk stratification and individualized counseling.