Blood pressure trajectories through the first year postpartum following a hypertensive disorder of pregnancy

BackgroundHypertensive disorders of pregnancy (HDP) are associated with future cardiovascular disease, predominantly through development of chronic hypertension, however the patterns of blood pressure recovery following a HDP are understudied. We sought to characterize the subtypes of hypertension (isolated systolic, isolated diastolic, systolic diastolic) and compare pregnancy and postpartum blood pressure trajectories among individuals with hypertensive disorders of pregnancy (HDP) who developed persistent hypertension at one year postpartum compared to individuals with normalization of blood pressure (BP). MethodsWe used data from a randomized controlled clinical trial of overweight and obese individuals with a physician adjudicated HDP conducted in the first year after delivery. Individuals with pre-pregnancy hypertension were excluded. Pregnancy BPs were obtained during prenatal visits, postpartum BPs were prospectively obtained through home BP monitoring, one week per month during the first year postpartum. Demographic characteristics and trajectories were compared based on whether or not individuals developed persistent hypertension (stage 1 or greater; systolic BP [&ge;]130, diastolic BP [&ge;]80 mmHg or use of anti-hypertensive medications) at one year. We further classified individuals with persistent hypertension as having isolated diastolic, isolated systolic and systolic diastolic hypertension. We used repeated BP measures to fit separate mixed-effects linear regression models for pregnancy and postpartum with participant identifier as random intercepts and weeks of pregnancy or months postpartum as a fixed effect expressed using restricted cubic splines. Models were compared using likelihood ratio test. ResultsWe included 129 individuals who contributed a mean of 95.4 (95%CI 76.7-115.1) BP readings during and following pregnancy. In total, 75 individuals (58%) progressed to stage 1 or stage 2 hypertension by 1 year postpartum. At one-year postpartum, among those with persistent hypertension, 43 (69%) had isolated diastolic hypertension, 2 (3%) had isolated systolic hypertension and 17 (27%) had systolic-diastolic hypertension. Individuals with persistent hypertension were about 2 years older, delivered at earlier gestational ages and tended to have a higher BMI at one year postpartum compared to those with BP normalization. There were no differences in BP at first prenatal visit or BP trajectories during pregnancy. Individuals with persistent hypertension had a more adverse BP trajectory (p<0.01 for systolic and diastolic BP) in the first year postpartum. These differences persisted in multivariable models after adjustment for pre-pregnancy BMI and type of HDP (p<0.01 for systolic and diastolic BP). ConclusionsBlood pressure trajectories in the first year postpartum, but not during pregnancy, may provide critical information for risk stratification after a HDP. In our study, a high proportion of individuals had ongoing hypertension, predominantly isolated diastolic hypertension. If confirmed in a larger cohort, this may provide insight into intervention development following a HDP. CLINICAL TRIALS REGISTRATION URL: https://clinicaltrials.gov/ct2/show/NCT03749746