A trajectory analysis of blood pressure development during pregnancy. An inception cohort study.

OBJECTIVES

To identify latent trajectories of blood pressure throughout pregnancy and evaluate their associations with body mass index (BMI), physical fitness (estimated via oxygen uptake), and serum relaxin levels in a cohort of healthy pregnant women.

STUDY

DESIGN

Prospective inception cohort study. Group-based trajectory modelling was used to characterize systolic and diastolic blood pressure patterns across gestation. Multiple logistic regression analyses were conducted to identify predictors of trajectory group membership.

MAIN OUTCOME MEASURES: Longitudinal trajectories of systolic and diastolic blood pressure during pregnancy.

RESULTS

A total of 492 women were included in early pregnancy. Three distinct and stable trajectories were identified for both systolic and diastolic blood pressure. Nulliparous women and those with BMI >25 kg/m2 had significantly increased odds of belonging to the highest blood pressure trajectory group (adjusted odds ratio [aOR] 2.47; 95% CI: 1.58-3.86 and aOR 1.61: 95% CI 1.04-2.49), respectively). No significant associations were observed between trajectory group membership and maternal age, physical fitness, or early-pregnancy serum relaxin concentrations.

CONCLUSIONS

Early pregnancy blood pressure may serve as a clinically relevant marker for gestational hypertension risk. Women with lower baseline readings may require less frequent antenatal monitoring, whereas those with elevated initial values could benefit from closer surveillance. Nulliparity and overweight status were associated with higher blood pressure trajectories, highlighting their relevance in antenatal risk stratification. Physical fitness and relaxin levels did not demonstrate predictive value in this context.