Is the "breast is best" mantra an oversimplification?

Hospitalization

Risk of infection is decreased. A large cohort study in Scotland, involving more than 500,000 children, found an association between exclusive breastfeeding for 6 to 8 weeks and decreased risk of hospitalization within the first 6 months of life. Formula-fed and mixed-fed infants had an increased hazard ratio (HR) for hospitalization for common childhood illness (HR=1.40; 95% CI, 1.35-1.45 for formula-fed infants and HR=1.18; 95% CI, 1.11-1.25 for mixed-fed infants).²⁷ The study also found increased rates of hospitalization for conditions for which other meta-analyses have failed to show a protective effect from breastfeeding—leading to suspicion of residual confounding in the study. Another United Kingdom cohort demonstrated lower rates of hospitalization for GI infection (NNT=171) and LRTI (NNT=115) among exclusively breastfed infants by 8 months of age.²⁸

Risk of neonatal readmission is increased. Late preterm infants who are exclusively breastfed are nearly twice as likely to be hospitalized as breastfed term or non-breastfed preterm infants, primarily due to dehydration, failure to thrive, weight loss, and hyperbilirubinemia. In fact, exclusive breastfeeding at discharge from the hospital is likely the single greatest risk factor for hospital readmission in newborns.^29,30 Term infants who are exclusively breastfed are more likely to be hospitalized compared to formula-fed or mixed-fed infants, due to hyperbilirubinemia, dehydration, hypernatremia, and weight loss (number needed to harm (NNH)=71).^30-32 For weight loss >10% of birth weight with or without hospitalization, the NNH for breastfed infants is 13.³²

Many of these hospitalizations and events could be avoided with appropriate monitoring and medically indicated supplementation; the likelihood of long-term harm is low. Formula supplementation is often avoided if possible in hospitals to promote exclusive breastfeeding; however, several small randomized clinical trials have demonstrated that limited formula supplementation in breastfed infants does not affect the breastfeeding continuation rate at 3 and 6 months, and, therefore, might be a way to decrease infant rehospitalization.^33,34

Necrotizing enterocolitis

Exclusive breastfeeding for 6 months is associated with a 43% reduction in the risk of acute otitis media by 2 years of age.

In preterm infants, breastfeeding has been associated with a lower rate of necrotizing enterocolitis. In the 2007 Agency for Healthcare Research and Quality report, the association was found to be only marginally statistically significant, and the authors warned that, first, evidence is old and heterogeneous and, second, present preterm formula is much different than the formula used in earlier studies of preterm infant nutrition and necrotizing enterocolitis.³⁵ A 2012 Cochrane review included newer studies in its analysis but reached the same conclusion on the quality and heterogeneity of available evidence, with a NNT of 25.³⁶

Continue to: Sudden infant death syndrome