A prospective study on maternal and neonatal outcomes and influencing factors in pregnant women with borderline hypertension

Objective To investigate maternal and neonatal outcomes and influencing factors in pregnant women with borderline hypertension.Methods This prospective cohort study consecutively enrolled 600 pregnant women receiving prenatal care at two hospitals between January 1 and December 31, 2024. Participants were divided into a normotensive control group (n = 300) and a borderline hypertension group (systolic 130–139 mmHg and/or diastolic 80–89 mmHg, n = 300). The primary outcome was progression to hypertensive disorders of pregnancy (HDP). Maternal and neonatal outcomes were compared, and influencing factors were analyzed.Results Women with borderline hypertension exhibited significantly higher rates of cesarean delivery (63.0% vs. 42.0%; p < 0.001), HDP progression (27.0% vs. 0.0%; p < 0.001), fetal growth restriction (15.7% vs. 2.7%; p < 0.001), and NICU admission (13.7% vs. 4.0%; p < 0.001) compared to normotensive controls. Notably, later gestational age at onset of borderline hypertension was identified as a protective factor against HDP progression (OR = 0.785 per week; 95% CI: 0.724–0.851; p < 0.001), corresponding to a 21.5% risk reduction for each delayed week of onset.Conclusion Borderline hypertension is associated with markedly increased adverse perinatal outcomes. Early detection and intervention—especially for women developing borderline elevation before 20 weeks—may help mitigate HDP progression. Integrating blood pressure trajectory monitoring into routine prenatal care is recommended.