Association between late pregnancy prehypertension and adverse outcomes among newborns of women delivered at a tertiary hospital in Eastern Uganda: a prospective cohort study

Prehypertension during pregnancy is currently not considered as a high-risk pregnancy state in existing guidelines despite recent research correlating it with higher rates of morbidity and mortality in both the mother and the fetus. Studies on prehypertension have not been conducted in Africa despite high rates of poor neonatal outcomes. The study aimed to determine the association between late pregnancy prehypertension and adverse outcomes in newborns of women with late pregnancy prehypertension at Jinja Regional Referral Hospital. Between September 2022 and January 2023, a hospital-based prospective cohort study including 300 pregnant women was conducted. Participants were divided according to third-trimester blood pressure, as determined by the JNC-8 criteria. Following hospital admission for labor and delivery, 150 normotensive women and 150 prehypertensive women were identified and followed until delivery, and their neonates were followed until death or hospital discharge. A p value of ≤ 0.05 was the threshold for statistical significance when comparing the groups using the relative risk, X2, and Mantel-Haenszel adjustment. Composite adverse neonatal outcomes were more common in prehypertensive women compared to normotensive women (48.67% versus 32.67%), particularly Small-for-Gestation Age (SGA), stillbirth, and composite adverse neonatal outcomes had significantly higher likelihood, with aRRs of 1.63 (95% CI 1.10–2.42, p = 0.037), 9.0 (95% CI 1.15–70.16, p = 0.010), and 1.55 (95% CI 1.16–2.08, p < 0.001), respectively. By a linear model, birthweight decreased by 45.1 g for every 10 mmHg rise in systolic blood pressure (p = 0.041, Pearson correlation of -0.118). Prehypertension in late pregnancy increased risks for adverse neonatal outcomes, thus a need to potentially lower pregnancy hypertension cut-off levels possibly through adopting the ACC/AHA blood pressure definitions for pregnant women.