Is the "breast is best" mantra an oversimplification?

Long-term outcomes

Cognitive development. Several studies conducted in developed countries have linked breastfeeding to positive cognitive outcomes in children, including higher intelligence quotient (IQ).^35,49-52

These effects are conflicting, however, in studies that include sibling analysis and ones that control for maternal IQ.^{8,35,43,52-54} In the 2013 WHO meta-analysis, breastfeeding was associated with an increase of 2.2 points on normalized testing when only high-quality studies were included.⁵¹ A 2015 meta-analysis identified 4 high-quality studies with a large sample size and recall time <3 years, which demonstrated a mean difference of 1.76 points in IQ (95% CI, 0.25-3.26) in childhood and adolescence.⁵² Although statistically significant, this modest increase is of questionable clinical benefit and of unknown duration.

Obesity. The relationship between breastfeeding and obesity later in life is debatable. A large, systematic 2014 review of 15 cohort and 10 cross-sectional studies found a significantly reduced risk of childhood obesity among children who were breastfed (adjusted OR=0.78; 95% CI, 0.74-0.81).⁵⁵ However, the review included studies that controlled for different confounders, and smaller effects were found in studies in which more confounders were taken into account.

Available data suggest that more than 3500 infants need to be breastfed to prevent one case of SIDS.

The 2013 WHO meta-analysis found a small (approximately 10%) reduction in the prevalence of overweight or obese children, but cautioned that residual confounding and publication bias were likely.⁵¹ At 6.5 and 11.5 years of follow-up, PROBIT failed to demonstrate a protective effect for exclusively or “ever” breastfed infants.⁵⁶ Sibling analysis similarly fails to demonstrate a statistically significant relationship.⁸

Continue to: A 2015 meta-analysis of 23 high-quality studies...