Abstract 18592: Association of Lactation Duration With Blood Pressure Recovery at One Year Postpartum in Overweight and Obese Individuals With a Hypertensive Disorder of Pregnancy

Abstract

Introduction: Hypertensive disorders of pregnancy (HDP) are associated with an increased risk of maternal cardiovascular (CV) disease. Lactation is associated with favorable metabolic and CV profiles, but its impact on blood pressure (BP) recovery following a HDP is less clear. Hypothesis: Longer lactation duration is associated with lower systolic and diastolic BP throughout the first year postpartum (PP). Methods: We utilized data from a randomized clinical trial of overweight and obese individuals with a HDP diagnosis and no pre-pregnancy hypertension. BP was assessed in triplicate along with self-reported lactation status at enrollment (6 weeks to 6 months PP) and follow up (8-12 months PP). Hypertension was defined as ≥130/80 mmHg or the use of anti-hypertensive medications. PP BPs were also obtained daily using home BP monitoring for the first six weeks, then one week per month for the remainder of the first year PP. We compared demographic and cardiometabolic outcomes by lactation status at both study visits using two-sample t-tests and chi-squared tests. We utilized multivariable logistic regression models to assess the relationship of lactation with hypertension and repeated BP measurements were fit to mixed-effects linear regression models by lactation status to assess BP recovery. Results: Data from 129 individuals included 14,177 home BPs. Overall, 81% of participants initiated lactation and mean lactation duration was 5.8 ± 4.0 months PP. At follow up (10.9 ± 2.1 months PP), both systolic (p=0.004) and diastolic (p=0.008) BP were lower in individuals who lactated compared to those who did not. Each month of lactation was associated with a 12% (aOR 0.88; 95% CI 0.78-0.98) decreased odds of hypertension at one year PP with adjustment for age, race, education, BMI. Lactating individuals had a healthier BP recovery profile (p<0.01 for systolic and diastolic BP) in the first year PP. Conclusions: In overweight and obese individuals with a HDP, lactation is associated with a statistically and clinically significant reduction in systolic and diastolic BP at one-year PP. This study emphasizes the need to address barriers to lactation to improve long-term CV health.