A steep-increasing blood pressure trajectory from early pregnancy is associated with birth outcomes in the EDEN mother-child cohort

Abstract

Background: An enhanced consideration of blood pressure (BP) dynamics during pregnancy could improve its monitoring. Distinct BP trajectories may exist, and some have been linked to adverse fetal development. Using maternal BP measurements spanning almost the entire pregnancy, this study aimed to identify trajectories and assess their association with birth outcomes.

Methods: Routine BP measurements (median = 8) were extracted from the obstetric records of 1849 mothers from the French EDEN birth cohort. Outcomes included birth weight z-score, prematurity and, for a subsample ( n = 1377), placental weight and birth weight-to-placental weight ratio. Maternal SBP trajectories were identified by Latent Class Growth Mixture Modeling. Associations with outcomes were analyzed using adjusted linear or logistic regressions.

Results: Two BP trajectories were identified: a first U-shaped and a second steep-increasing, comprising 96 and 4% of mothers, respectively. The steep-increasing trajectory reached the hypertensive threshold around 30 weeks of gestation. Over half of mothers in this trajectory had a hypertensive disorder diagnosis, and 24% had preeclampsia. Mothers in this trajectory had newborns with lower birth weight z-scores [β = -0.31, 95% confidence interval (95% CI) = -0.55 to -0.07] and/or increased likelihood of premature delivery (odds ratio = 4.02, 95% CI = 2.04-7.50). No associations were observed with placental outcomes.

Conclusion: Our results suggest the existence of a steep-increasing BP trajectory from the first weeks of pregnancy and associated with poorer birth outcomes. Further investigation into this trajectory's determinants could lead to improved hypertensive disorder risk stratification, ultimately aiding in the prevention of related maternal and fetal consequences.

Keywords: birth cohort; birth weight; blood pressure; hypertension; placenta; pre-eclampsia; pregnancy; risk assessment.

FIGURE 1

Study inclusion flowchart.

FIGURE 2

(a) Average maternal SBP and 95% confidence intervals of the mean at each week of gestation. (b) Two trajectories of maternal SBP across gestation identified using Latent Class Growth Mixture Modeling.