Breastfeeding duration and subsequent risk of mortality among US women: A prospective cohort study. (December 2022)

• Record Type: Journal Article
• Authors: Wang, Yi-Xin; Arvizu, Mariel; Rich-Edwards, Janet W.; Manson, JoAnn E.; Wang, Liang; Missmer, Stacey A.; Chavarro, Jorge E.
• Is Part Of: EClinicalMedicine. Volume 54(2022)
• Publication Date: 2022-12
• Subjects: Breastfeeding duration -- Mortality -- Cohort study -- Women's health; Medicine -- Research -- Periodicals; Medical policy -- Periodicals; Clinical Medicine; Health Policy; Public Health; Medical policy; Medicine -- Research; Periodical; Electronic journals; Periodicals; 613
• DOI: 10.1016/j.eclinm.2022.101693
• Languages: English
• ISSNs: 2589-5370

Abstract

Summary: Background: Breastfeeding has been associated with a reduced maternal long-term risk of chronic diseases, but its association with mortality is poorly known. Methods: We included 166, 708 female United States (US) nurses from the Nurses' Health Study (1986-2016) and the Nurses' Health Study II (1989-2019) who experienced at least one pregnancy lasting at least six months across their reproductive lifespan. Hazard ratios and 95% confidence intervals (CI) for mortality according to lifetime breastfeeding duration were estimated with time-dependent Cox proportional hazards regression models. Findings: During 4, 705, 160 person-years of follow-up, 36, 634 deaths were documented in both cohorts, including 9880 from cancer and 7709 from cardiovascular disease (CVD). Lifetime total breastfeeding duration was associated with a lower subsequent risk of all-cause mortality in a non-linear manner (p-value for non-linearity=0.0007). The pooled multivariable-adjusted hazard ratios of all-cause mortality were 0.95 (95% CI: 0.92 to 0.98), 0.94 (95% CI: 0.91 to 0.98), 0.93 (95% CI: 0.90 to 0.97), and 0.93 (95% CI: 0.89 to 0.97), respectively, for women reporting lifetime total breastfeeding duration of 4–6, 7–11, 12–23, and ≥24 months, compared to women who breastfed for ≤3 months over their reproductive lifespan. Cause-specific analysis showed a similar pattern of non-linear inverse associations between lifetime total breastfeeding duration and CVD and cancer mortality (both p-values for non-linearity <0.01). There was no evidence of interactions between breastfeeding duration and pre-pregnancy lifestyle factors on mortality risk. Interpretation: Parous women with longer lifetime breastfeeding duration had a modestly lower risk of mortality. Funding: The National Institutes of Health grants.