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).
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.
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)].