Peer-reviewed article
Assessing the impact of maternal blood pressure during pregnancy on perinatal health: a wide-angled Mendelian randomization study.
Morales-Berstein F, Gonçalves-Soares A, Yang Q, McBride N, Bond T et al. ·
Summary
Written by AI, not yet AICS's view · claude-haiku-4-5-20251001This study used genetic data from over one million people to examine whether high blood pressure during pregnancy causes adverse outcomes for babies. The researchers found that higher maternal blood pressure was causally linked to several serious complications including low birth weight, premature birth, and the need for neonatal intensive care. The findings suggest that controlling blood pressure during pregnancy could reduce harm to newborns.
Key points
- A 10 mmHg increase in maternal systolic blood pressure increased odds of low birth weight by 33% (OR 1.33) and neonatal intensive care unit admission by 11% (OR 1.11)
- Higher maternal blood pressure increased risks of gestational diabetes, induction of labour, small-for-gestational age, and preterm birth
- Higher maternal blood pressure decreased odds of high birth weight and large-for-gestational age babies
- No causal relationship found between maternal blood pressure and miscarriage or stillbirth
- Results were consistent across multiple sensitivity analyses accounting for genetic confounding
Limitations
The study used genetic data predominantly from European ancestry populations, so findings may not generalise to other populations. Mendelian randomization is a proxy for causation based on genetic variation and assumes certain conditions about how genes work.
Abstract
Background Observational studies link high blood pressure in pregnancy to numerous adverse pregnancy and perinatal outcomes; however, findings may be affected by residual confounding or reverse causation. This study aimed to assess the causal effect of blood pressure during pregnancy on a range of pregnancy and perinatal outcomes. Methods We performed two-sample Mendelian randomization (MR) to assess the effect of systolic and diastolic blood pressure (SBP/DBP) during pregnancy on 16 primary and eight secondary adverse pregnancy and perinatal outcomes. We obtained genetic association data from large-scale meta-analyses of genome-wide association studies involving predominantly European ancestry individuals for SBP/DBP (N = 1,028,980), and pregnancy and perinatal outcomes (N = 74,368-714,899). We used inverse-variance weighted (IVW) MR for main analyses and MR-Egger, weighted median, weighted mode, multivariable MR, and IVW adjusted for fetal genetic effects for sensitivity analyses. Results A 10 mmHg higher genetically predicted maternal SBP increased the odds of gestational diabetes, induction of labour, low birth weight (LBW), small-for-gestational age (SGA), preterm birth (PTB), and neonatal intensive care unit (NICU) admission (OR ranging from 1.11 [95% CI 1.02 to 1.20] for NICU admission to 1.33 [1.26 to 1.41] for LBW); while decreasing the odds of high birth weight (HBW), large-for-gestational age (LGA), and post-term birth [OR ranging from 0.76 (0.69 to 0.83) for HBW to 0.94 (0.90 to 0.99) for post-term birth]. We did not find evidence that genetically predicted higher maternal SBP was related to miscarriage or stillbirth. The results for maternal DBP were similar to the results for SBP. Overall, the main results were consistent across sensitivity analyses accounting for pleiotropic instruments and fetal genetic effects. Conclusions Higher maternal blood pressure reduces gestation duration and fetal growth and increases the risks of induction of labour, gestational diabetes, and neonatal intensive care unit admission. This and other emerging evidence highlight the value of interventions aimed at controlling blood pressure in the population to reduce the burden of adverse pregnancy outcomes.