Outcomes of Postpartum Preeclampsia: A Retrospective Cohort Study of 1.3 Million Pregnancies.

Objective: We assessed the association between postpartum preeclampsia and the risk of adverse maternal and neonatal outcomes. Evidence suggests that postpartum preeclampsia is initiated antenatally, but the impact on birth outcomes is unclear.

Design: Retrospective cohort study.

Setting: All deliveries in hospitals of Quebec, Canada.

Population: 1 317 181 pregnancies between 2006 and 2022.

Methods: We identified patients who developed preeclampsia in the postpartum period. Using log-binomial regression models, we estimated adjusted risk ratios (RR) and 95% confidence intervals (CI) for the association of postpartum or antepartum preeclampsia with adverse pregnancy outcomes relative to no preeclampsia.

Main Outcome Measures: Preterm birth, placental abruption, severe maternal morbidity and recurrent preeclampsia.

Results: Postpartum preeclampsia was less frequent than antepartum preeclampsia (n = 4123 [0.3%] vs. 51 269 [3.9%]). Postpartum preeclampsia was associated with preterm birth (RR 1.45, 95% CI 1.34-1.57), placental abruption (RR 1.36, 95% CI 1.16-1.59) and severe maternal morbidity (RR 6.48, 95% CI 5.87-7.16) compared with no preeclampsia. Antepartum preeclampsia was also associated with these outcomes. Moreover, patients with postpartum preeclampsia in a first pregnancy were at risk of adverse outcomes in a subsequent pregnancy, particularly recurrent preeclampsia (RR 7.77, 95% CI 6.54-9.23).

Conclusions: Postpartum preeclampsia is associated with adverse outcomes at delivery, despite being detected only postnatally. Our findings suggest that patients with adverse birth outcomes may benefit from blood pressure measurements up to 6 weeks following delivery.