Association of pre-/early pregnancy high blood pressure and pregnancy outcomes: a systemic review and meta-analysis.

Background: Maternal high blood pressure (BP) was associated with adverse pregnancy outcomes. This study aimed to synthesize evidence on the association between high BP prior to or in early pregnancy with maternal and fetal complications.

Methods: We searched the cohort studies assessing the effect of high BP in the Medline, Embase, Web of Science and China National Knowledge Internet databases. A random-effects model was used to estimate the pooled odds ratios (ORs) with 95% confidence intervals (CIs). The protocol was registered in PROSPERRO (CRD 42023414945).

Results: 23 eligible studies were identified. High BP prior to or in early pregnancy was associated with higher odds of hypertensive disorders of pregnancy (OR 2.90, 95% CI 1.91-3.89), gestational hypertension (2.56, 2.01-3.12), preeclampsia (3.20, 2.66-3.74), gestational diabetes mellitus (1.71, 1.36-2.06), preterm birth (1.66, 1.39-1.93), stillbirth (2.01, 1.45-2.58) and neonatal intensive care unit admission (1.22, 1.08-1.37). Subgroup analyses indicated that pre-hypertension could significantly increase the odds of these outcomes except for stillbirth, though the odds were lower than hypertension.

Conclusions: High BP prior to or in early pregnancy was associated with adverse pregnancy outcomes and this association increased with hypertension severity. The findings emphasized an urgent need for heightened surveillance for maternal BP, especially pre-hypertensive status.