Breastfeeding initiation and duration among people with mild chronic hypertension: A secondary analysis of the Chronic Hypertension and Pregnancy (CHAP) trial.

Overview

abstract

BACKGROUND: Increased duration of breastfeeding improves maternal cardiovascular health and may be especially beneficial in high-risk populations, such as those with chronic hypertension. Others have shown that individuals with hypertension are less likely to breastfeed, and there has been limited research aimed at supporting breastfeeding goals in this population. The impact of perinatal blood pressure control on breastfeeding outcomes among people with chronic hypertension is unknown. OBJECTIVE: The aim of this study was to evaluate whether breastfeeding initiation and short-term duration assessed at the postpartum clinic visit differed based on perinatal blood pressure treatment strategy (targeting blood pressure <140/90 mm Hg vs. reserving antihypertensive treatment for blood pressure ≥160/105 mm Hg). STUDY DESIGN: We performed a secondary analysis of the Chronic Hypertension and Pregnancy (CHAP) Trial. This was an open-label, multicenter, randomized trial where pregnant participants with mild chronic hypertension were randomized to receive antihypertensive medications with goal blood pressure <140/90 mm Hg (active treatment) or deferred treatment until blood pressure ≥160/105 mm Hg (control). Primary outcome was initiation and duration of breastfeeding, assessed at the postpartum clinic visit. We performed bivariate analyses and log-binomial and cumulative logit regression models, adjusting models for variables that were unbalanced in bivariate analyses. We performed additional analyses to explore the relationship between breastfeeding duration and blood pressure measurements at the postpartum visit. RESULTS: 1444/2408 (60%) participants from the CHAP trial attended the postpartum study visit and provided breastfeeding information. Participants in the active treatment group had different body mass index class distribution and earlier gestational age at enrollment, and (by design) were more often discharged on antihypertensives. Breastfeeding outcomes did not differ significantly by treatment group. In the active and control treatment groups, 563 (77.5%) and 561 (78.1%) initiated breastfeeding, and mean duration of breastfeeding was 6.5 ± 2.3 and 6.3 ± 2.1 weeks, respectively. The probability of ever breastfeeding (aRR 0.99, 95% CI 0.93-1.05), current breastfeeding at postpartum visit (aRR 1.01, 95% CI 0.94-1.10), and weeks of breastfeeding (aOR 0.87, 95% CI 0.68-1.12) did not differ by treatment group. Increased duration (≥2 weeks vs. <2 weeks) of breastfeeding was associated with slightly lower blood pressure measurements at the postpartum visit, but these differences were not significant in adjusted models. CONCLUSIONS: In a secondary analysis of the cohort of CHAP participants who attended the postpartum study visit and provided breastfeeding information (60% of original trial participants), breastfeeding outcomes did not differ significantly by treatment group. This suggests that maintaining goal blood pressure <140/90 mm Hg throughout the perinatal period is associated with neither harm nor benefit for short-term breastfeeding goals. Further study is needed to understand long-term breastfeeding outcomes among individuals with chronic hypertension and how to support this population in achieving their breastfeeding goals.