Objective: Preeclampsia, small for gestational age (SGA), and abruption are considered ischemic placental diseases (IPD), and are major contributors to both maternal and fetal morbidity and mortality. Although the placenta is considered a fetal organ, these conditions can present clinically with either maternal or fetal manifestations, but their relationship to preterm births is largely unexplored.
Methods: We designed a population-based study to assess the origins of IPD. IPD was classified as maternal (preeclampsia only), fetal (SGA only), or both (abruption only, preeclampsia with either SGA or abruption, or all 3). The study was based on 90,500 women that delivered singleton live births at 22-44 weeks gestation.
Results: Among 77,275 term births with IPD, 23.2% presented as maternal disease only, 68.9% as fetal disease, and 7.9% as both. In contrast, among 12,906 preterm births with IPD, the proportions were roughly equal (maternal 32.9%, fetal 36.5%, and both 30.6%). Among spontaneous preterm births with IPD, a greater proportion had a fetal presentation (43.0%), whereas among indicated preterm births with IPD, a greater proportion (43.4%) had both maternal and fetal presentations.
Conclusions: IPD at preterm gestations is more likely to involve both the mother and fetus than at term. The differing clinical presentations by gestational age suggest different pathways between term and preterm births. This may reflect heterogeneous processes for IPD at early vs. late gestations, regardless of the effects of differing gestational age thresholds for interventions.