89 - Preterm birth as a risk factor for postpartum preeclampsia

Publication Number: 3085.89

Kristan Scott, Childrens Hospital of Philadelphia, Philadelphia, PA, United States; Rachel F. Ledyard, Children's Hospital of Philadelphia, Philadelphia, PA, United States; Taneisha Sinclair, Children's Hospital of Philadelphia, Philadelphia, PA, United States; Timothy Nelin, Childrens Hospital of Philadelphia, Philadelphia, PA, United States; EMILY GREGORY, Children's Hospital of Philadelphia, PHILADELPHIA, PA, United States; Celeste Durnwald, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, United States; Heather Burris, Children's Hospital of Philadelphia, Philadelphia, PA, United States

Background: Preeclampsia affects approximately 2-8% of pregnancies and is a leading cause of maternal morbidity, mortality, and medically indicated preterm birth (PTB). Preeclampsia can also occur de novo, postpartum, accounting for 5-10% of all preeclampsia cases. A Canadian study reported that individuals with postpartum preeclampsia were 45% more likely to have had a PTB than a term birth; however, this study did not exclude patients with pre-existing hypertension, a known risk factor for preeclampsia that often prompts intensive postpartum blood pressure (BP) monitoring. Whether PTB is associated with postpartum preeclampsia among previously normotensive parents is unknown, but important as delayed diagnosis and treatment can lead to severe cardiovascular complications.

Objective: To determine if PTB is associated with postpartum preeclampsia in a previously normotensive cohort.

Design/Methods: Retrospective cohort study of live births from 2008-2019 in GeoBirth, a curated dataset from 2 Philadelphia hospitals, with prenatal and postpartum visit data. Bivariate analyses examined characteristics associated with postpartum preeclampsia. Multivariable, modified Poisson regression models calculated risk ratios (RR) of postpartum preeclampsia after PTB ( < 37 weeks'), compared to term births. Secondarily, we assessed RRs of postpartum preeclampsia after late (34- < 37 weeks' gestation) and early ( < 34 weeks' gestation) PTB compared to term birth. Models adjusted for age, parity, body mass index, race and ethnicity, education, singleton gestation, and mode of birth.

Results: Of the 39,296 individuals without hypertension during pregnancy, 282 (0.72%) had postpartum preeclampsia. Higher postpartum preeclampsia rates were observed among individuals with the following characteristics: multiparity; BMI ≥ 30 kg/m2; non-Hispanic Black race; some college education; multiple gestations; cesarean birth; and NICU admission (Table 1). Individuals with PTB were more than twice as likely to develop de novo postpartum preeclampsia than those with term births (1.76% vs. 0.64%, P< 0.001), an association that persisted with multivariable adjustment (aRR 2.34, 95% CI: 1.69, 3.23) (Figure 1). Individuals with early PTB ( < 34 weeks) had the highest risk of postpartum preeclampsia (aRR 2.64, 95% CI: 1.62, 4.33).

Conclusion(s): PTB was associated with postpartum preeclampsia among previously normotensive individuals. Targeted postpartum BP monitoring of parents of preterm infants, particularly within NICU and pediatric settings, may facilitate early detection and treatment for this high-risk group and prevent morbidity and mortality.

Table 1
Characteristics of previously normotensive parents, with prenatal and postpartum visit data, stratified by postpartum preeclampsia at 2 Philadelphia birth hospitals, 2008−2019 (n=39,296).

Figure 1
Unadjusted and adjusted risk ratios (95% Confidence Intervals) of postpartum preeclampsia in gestational age bins (all PTB <37 weeks' gestation, late PTB 34-37 weeks', and early PTB 22- <34 weeks') compared to full-term births. Models adjusted for following covariates: age; parity; body mass index; race and ethnicity; education; singleton gestation; and mode of birth.