SynthesisBMC medicine2025
The influence of fetal sex on maternal blood pressure in pregnancy.
Synthesis in BMC medicine, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 1 paper.
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
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1 citing paper in PubMed.
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12 authors.
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Abstract
backgroundPregnancy with a male compared to a female fetus carries a higher risk of term pre-eclampsia. Given evidence that maternal blood pressure (BP) may be raised in pregnancies with Beckwith-Wiedemann syndrome (fetal overgrowth), a possible contributor to the association between male sex and term pre-eclampsia is faster male growth (~ 130 g heavier than females). We hypothesized that male sex would be associated with higher maternal BP in a general population sample, explained by birth weight sex differences.
methodsWe tested the association between fetal sex and maternal systolic (SBP) and diastolic blood pressure (DBP), measured at ~ 28 weeks gestation, in a meta-analysis of five cohorts of mother-child pairs (n up to 109,842). Maternal BP was analyzed as a continuous and dichotomized (high BP yes/no) outcome. Linear regression models were constructed with and without adjustment for birth weight to assess whether any difference in maternal BP was explained by birth weight differences between male and female babies. Lastly, we constructed a fetal genetic score for birth weight using 186 own-birth-weight-associated single-nucleotide polymorphisms (SNPs) to test whether fetal birth-weight-raising-alleles were associated with maternal BP in pregnancy (n up to 32,232).
resultsMaternal SBP and DBP were higher in pregnancy when carrying a male compared to a female fetus (mean difference 0.35 mmHg [95% CI: 0.15-0.55] and 0.35 mmHg [95% CI: 0.21-0.49], for SBP and DBP, respectively). An independent effect of fetal sex remained when including birth weight but attenuated slightly (0.22 mmHg [95% CI: 0.02-0.42] and 0.31 mmHg [95% CI: 0.17-0.45], for SBP and DBP, respectively). While there was a positive direction of effect for odds of high maternal BP given pregnancy with a male fetus, confidence intervals included the null (OR 1.05 [95% CI: 0.98-1.12]). No evidence for an association was found between a fetal birth weight genetic score and SBP or DBP when conditioned on maternal genotype.
conclusionsWe found strong evidence to support a small effect of male fetal sex on higher maternal BP in pregnancy, without substantial contribution from larger fetal size at birth. Our findings do not indicate a difference in maternal BP that would warrant changes to routine clinical practice.
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