Abstract
Objective The burden of preeclampsia severity on the health of mothers and infants during the
first year after delivery is unclear, given the lack of population-based longitudinal
studies in the United States.
Study design We assessed maternal and infant adverse outcomes during the first year after delivery
using population-based hospital discharge information merged with vital statistics
and birth certificates of 2,021,013 linked maternal–infant births in California. We
calculated sampling weights using the National Center for Health Statistics data to
adjust for observed differences in maternal characteristics between California and
the rest of the United States. Separately, we estimated the association between preeclampsia
and gestational age and examined collider bias in models of preeclampsia and maternal
and infant adverse outcomes.
Results Compared with women without preeclampsia, women with mild and severe preeclampsia
delivered 0.66 weeks (95% confidence interval [CI]: 0.64, 0.68) and 2.74 weeks (95%
CI: 2.72, 2.77) earlier, respectively. Mild preeclampsia was associated with an increased
risk of having any maternal adverse outcome (relative risk [RR] = 1.95; 95% CI: 1.93,
1.97), as was severe preeclampsia (RR = 2.80; 95% CI: 2.78, 2.82). The risk of an
infant adverse outcome was increased for severe preeclampsia (RR = 2.15; 95% CI: 2.14,
2.17) but only marginally for mild preeclampsia (RR = 0.99; 95% CI: 0.98, 1). Collider
bias produced an inverse association for mild preeclampsia and attenuated the association
for severe preeclampsia in models for any infant adverse outcome.
Conclusion Using multiple datasets, we estimated that severe preeclampsia is associated with
a higher risk of maternal and infant adverse outcomes compared with mild preeclampsia,
including an earlier preterm delivery.
Keywords
maternal morbidity - perinatal morbidity - preeclampsia - severe features
