Preconception and first trimester blood pressure: risks of hypertensive disorders in pregnancy using AHA guidelines

To evaluate the risk of hypertensive disorders of pregnancy (HDP) according to the 2017 American Heart Association (AHA) blood pressure (BP) categories based on preconception and early pregnancy measurements.

This retrospective cohort study included nulliparous singleton pregnancies (2010-2023) with at least one BP measurement from one year before conception through 13 weeks' gestation. Women with chronic hypertension were excluded. Participants were classified as normotensive, elevated BP (systolic BP 120-129 mmHg and diastolic BP <80 mmHg), or stage 1 hypertension (systolic BP 130-139 mmHg or diastolic BP 80-89 mmHg). The primary outcome was composite HDP, including preeclampsia, eclampsia, or HELLP syndrome. Logistic regression adjusted for maternal age, aspirin use, BMI, and pregestational diabetes mellitus (PGDM). Subgroup analyses were performed for obesity (BMI ≥30) and PGDM.

Among 57,524 women, 81.6% were normotensive, 11.5% had elevated BP, and 6.9% had stage 1 hypertension. Composite HDP rates increased in a dose-response manner (2.8%, 6.4%, and 8.2%, respectively; p < 0.001). Both elevated BP and stage 1 hypertension were independently associated with HDP (adjusted odds ratios [aOR] 2.22, 95% CI 1.94-2.55, and 2.75, 95% CI 2.34-3.24). Similar associations were observed in women with obesity and PGDM, with particularly high risk among those with elevated BP and PGDM (aOR 2.88, 95% CI 1.89-4.20).

Preconception and first-trimester elevated BP and stage 1 hypertension are associated with substantially increased HDP risk, supporting early BP-based risk stratification, especially in high-risk populations.