Hypertensive disorders of pregnancy and breastfeeding practices: A secondary analysis of data from the All Our Families Cohort

Introduction Hypertensive disorders of pregnancy occur in approximately 7%-10% of pregnancies and are associated with adverse maternal cardiovascular health outcomes across the lifespan. In contrast, breastfeeding has been associated with a reduction in cardiovascular risk factors in a dose-dependent manner. Despite the potential protective effects of lactation on cardiovascular risk, how hypertensive disorders of pregnancy relate to breastfeeding practices and experiences is not well understood. The aim of this study was to investigate the association between hypertensive disorders of pregnancy and breastfeeding outcomes in the first year postpartum. Material and methods We conducted a secondary analysis of prospective data from the All Our Families Cohort, a population-based study conducted in Calgary, Alberta, Canada. Women with a singleton pregnancy (n = 1418) who completed self-report questionnaires at <25 weeks and 34-36 weeks of gestation, and 4 months and 12 months postpartum, and provided consent to link to electronic medical records that identified diagnoses of hypertensive disorders of pregnancy (n = 122). Logistic and multiple linear regression analyses were used to model associations between hypertensive disorders of pregnancy and breastfeeding outcomes. Outcomes included breastfeeding intention, intended duration, exclusive breastfeeding at 4 months, breastfeeding duration at 12 months and breastfeeding difficulties. Results Hypertensive disorders of pregnancy were not associated with breastfeeding intention (odds ration [OR] 1.30, 95% confidence interval [CI] 0.47-3.03, P = 0.57), intended breastfeeding duration (b = -3.28, 95% CI -7.04 to 0.48, P = 0.09), or initiation (OR = 0.64, 95% CI 0.29- 1.65, P = 0.32), but were associated with an increase in the odds of non-exclusive breastfeeding at 4 months postpartum (OR = 2.11, 95% CI 1.39-3.22, P < 0.001). Women with hypertensive disorders breastfed for 6.26 (95% CI -10.00 to -2.51, P < 0.001) weeks less over 12 months postpartum, had significantly higher odds of reporting insufficient milk supply (OR = 1.75, 95% CI 1.19-2.46, P < 0.05) and had lower odds of breast and/or nipple pain (OR = 0.66, 95% CI 0.44-0.92, P < 0.05) compared with those without hypertensive disorders of pregnancy. Conclusions Hypertensive disorders of pregnancy are associated with altered breastfeeding practices and experiences during the first year postpartum. Further research is needed to examine biopsychosocial mechanisms through which hypertensive disorders associate with shorter breastfeeding duration, and to examine whether greater breastfeeding duration, intensity or exclusivity reduces short- or long-term maternal cardiovascular risk.