Breastfeeding and post-perinatal infant deaths in the United States, A national prospective cohort analysis

BACKGROUND: Reducing infant mortality is a major public health goal. The potential impact of breastfeeding on infant deaths is not well studied in the United States (US). METHODS: We analyzed linked birth−death certificates for 3,230,500 US births that occurred in 2017, including 6,969 post-perinatal deaths from 7−364 days of age as the primary outcome, further specified as late-neonatal (7−27 days) or post-neonatal (28−364 days) deaths. The primary exposure was ‘ever breastfed’ obtained from birth certificates. Multiple logistic regression examined associations of ever breastfeeding with post-perinatal deaths and specific causes of deaths, controlling for maternal and infant factors. FINDINGS: We observed an adjusted reduced odds ratio (AOR)=0·74 with 95% confidence intervals (CI)=0·70–0·79 for the association of breastfeeding initiation with overall infant deaths (7−364 days), AOR=0·60 (0·54–0·67) for late-neonatal deaths, and AOR=0·81 (0·76–0·87) for post-neonatal deaths. In race/ethnicity-stratified analysis, significant associations of breastfeeding initiation with reduced odds of overall infant deaths were observed for Hispanics [AOR=0·64 (0·55−0·74)], non-Hispanic Whites [AOR=0·75 (0·69−0·81)], non-Hispanic Blacks [AOR=0·83 (0·75−0·91)], and non-Hispanic Asians [AOR=0·51 (0·36−0·72)]. Across racial/ethnic groups, effect sizes for late-neonatal deaths were consistently larger than those for post-neonatal deaths. Significant effects of breastfeeding initiation were observed for deaths due to infection [AOR=0·81(0·69–0·94)], Sudden Unexpected Infant Death [AOR=0·85 (0·78–0·92)], and necrotizing enterocolitis [AOR=0·67 (0·49−0·90)]. INTERPRETATION: Breastfeeding initiation is significantly associated with reduced odds of post-perinatal infant deaths in multiple racial and ethnic groups within the US population. These findings support efforts to improve breastfeeding in infant mortality reduction initiatives.