Longitudinal maternal cardiac function in hypertensive disorders of pregnancy.

Background: Compared with gestational hypertension, preeclampsia has traditionally been considered the worse end of the spectrum of hypertensive disorders of pregnancy. It is associated with worse pregnancy outcomes and future cardiovascular morbidities. Both hypertensive disorders may be associated with cardiac maladaptation in pregnancy. However, previous studies were limited by small numbers and a paucity of longitudinal data and unaccounted for the contribution of maternal characteristics that can affect hemodynamics.

Objective: This study aimed to assess, in an unselected population, the maternal cardiac adaptation in normotensive and hypertensive pregnancies after controlling for important maternal characteristics that affect maternal cardiac function and the interaction among these covariates.

Study Design: This was a prospective, multicenter longitudinal study of maternal hemodynamics, assessed by a noninvasive bioreactance technology, measured at 11 0/7 to 13 6/7, 19 0/7 to 24 0/7, 30 0/7 to 34 0/7, and 35 0/7 to 37 0/7 weeks of gestation in 3 groups of women. Group 1 was composed of women with preeclampsia (n=45), group 2 was composed of women with gestational hypertension (n=61), and group 3 was composed of normotensive women (n=1643). A multilevel linear mixed-effects model was performed to compare the repeated measures of hemodynamic variables controlling for maternal age, height, weight, weight gain, race, previous obstetrical history, and birthweight.

Results: After adjusting for confounders that significantly affect maternal hemodynamics, both group 1 and group 2, compared with group 3, had pathologic cardiac adaptation. Group 1, compared with group 3, demonstrated hyperdynamic circulation with significantly higher cardiac output driven by greater stroke volume in the first trimester of pregnancy. As the pregnancies progressed to after 20 0/7 weeks of gestation, this hyperdynamic state transitioned to hypodynamic state with low cardiac output and high peripheral vascular resistance. Group 2, compared with group 3, had no significant differences in cardiac output, stroke volume, and heart rate before 20 0/7 weeks of gestation but thereafter demonstrated a continuous decline in cardiac output and stroke volume, similar to group 1. Both groups 1 and 2, compared with group 3, had persistently elevated mean arterial pressure and uterine artery pulsatility index throughout pregnancy.

Conclusion: After adjusting for confounders that affect maternal hemodynamics in an unselected pregnant population, women with preeclampsia and gestational hypertension, compared with normotensive women, demonstrated similar cardiac maladaptation. This pathologic profile was evident after 20 0/7 weeks of gestation and at least 10 weeks before the clinical manifestation of the disease.