Breastfeeding initiation and duration and child health outcomes in the first baby study

Despite the known benefits of breastmilk, associations between breastfeeding and child overall health outcomes remain unclear. We aimed to understand associations between breastfeeding and health outcomes, including child weight, through age 3. Analysis included women (N = 3006) in the longitudinal, prospective First Baby Study from 2009 to 2014. For this analysis, breastfeeding initiation and duration were measured using self-reported data from the 1-, 6- and 12-month surveys; child illnesses were analyzed from the 6-, 12-, and 24-month interviews; height and weight at age 3 were used to determine overweight/obese (≥85th percentile) and obese (≥95th percentile). Adjusted logistic regressions were utilized to determine significance. Greater duration of breastfeeding was associated with fewer reported acute illnesses at 6 months (p < 0.001) and fewer diarrheal illness/constipation episodes at 6, 12, and 24 months (p = 0.05) in adjusted analyses. Fewer breastfed children, compared to non-breastfed children, were overweight/obese (23.5% vs. 37.8%; p = 0.032) or obese (9.1% vs. 21.6%; p = 0.012) at age 3. Breastfeeding duration was negatively associated with overweight/obese (never breastfed: 37.8%, 0–6 months: 26.9%, >6 months: 20.2%; p = 0.020) and obesity (never breastfed: 21.6%, 0–6 months: 11.0%, >6 months: 7.3%; p = 0.012). Overall, our findings support the hypothesis that duration of breastfeeding is associated with fewer reported acute illnesses at 6 months of age and diarrheal illness and/or constipation episodes at 6, 12, and 24 months. Additionally, results from our study suggest a protective effect of breastfeeding from childhood overweight/obesity, as children who received breastmilk for 6 months or longer had lower odds of overweight/obesity at age 3 years.