Background:

Hypertensive disorders of pregnancy (HDPs) are associated with an increased risk of long-term maternal cardiovascular disease. Lactation is associated with favorable cardiometabolic profiles, but its impact on blood pressure (BP) recovery following an HDP is less clear.

Objective:

We sought to assess the relationship of lactation initiation and duration with BP among individuals with prior HDP.

Materials and Methods:

We used prospectively collected data from individuals with prepregnancy overweight or obesity with HDP and no prepregnancy hypertension who participated in a postpartum pilot lifestyle intervention trial. The parent trial assessed BP in triplicate and self-reported lactation status at enrollment and follow-up (8–12 months postpartum) study visits. Daily BPs were obtained by home BP monitoring for the first 6 weeks postpartum, then 1 week per month for the remainder of the first year postpartum. Hypertension was defined as BP ≥ 130/80 mmHg or the use of antihypertensive medications. We compared demographic and cardiometabolic outcomes by lactation initiation and created multivariable logistic regression models adjusted for age, race, education, and prepregnancy body mass index (BMI) to assess the relationship of lactation with hypertension.

Results:

Data from 129 individuals included 14,177 home BPs. Overall, 81% of participants initiated lactation, and median lactation duration was 6 months [Interquartile range (IQR) 2,9]. At follow-up (10.9 ± 2.1 months postpartum), both systolic (SBP; p = 0.004) and diastolic (DBP; p = 0.008) BP were lower in individuals who initiated lactation compared with those who did not. Each month of lactation was associated with a 12% [adjusted odds ratio 0.88; 95% confidence interval (CI) 0.78–0.98] decreased odds of hypertension at 1 year postpartum with adjustment for age, race, education, and BMI.

Conclusions:

In overweight and obese individuals with an HDP, lactation is associated with a significant reduction in SBP and DBP at 1 year postpartum and throughout the first year postpartum.

Clinical Trials Registration:

https://clinicaltrials.gov/ct2/show/NCT03749746.