Optimal breastfeeding of infants under two years of age has the greatest potential impact on child survival of all preventive interventions, with the potential to prevent over 800,000 deaths (13 per cent of all deaths) in children under five in the developing world (Lancet 2013).
In fact, UNICEF feels pretty strongly about supporting breastfeeding:
Formula is not an acceptable substitute for breastmilk because formula, at its best, only replaces most of the nutritional components of breast milk: it is just a food, whereas breast milk is a complex living nutritional fluid containing anti-bodies, enzymes, long chain fatty acids and hormones, many of which simply cannot be included in formula. Furthermore, in the first few months, it is hard for the baby’s gut to absorb anything other than breastmilk. Even one feeding of formula or other foods can cause injuries to the gut, taking weeks for the baby to recover.
The major problems are the societal and commercial pressure to stop breastfeeding, including aggressive marketing and promotion by formula producers.
Eva Seidelman and Lisa McCloskey explore this theme some more:
The Centers for Disease Control and Prevention reports that more than half of U.S. hospitals give commercial infant formula samples to new mothers. Hospitals typically hand out these samples regardless of whether moms intend to breastfeed. There is abundant evidence that these free samples lead mothers to formula feed sooner and more frequently than they intended.
Seidelman and McCloskey go further, saying this practice — intended to market infant formula to all mothers in a newborn nursery — has unintended consequences:
The “free” infant formula samples that hospitals hand out come with very real costs. In-hospital formula marketing contributes to premature breastfeeding discontinuation — contravening the consensus of health care experts that breastfeeding gives children the best start and shields them from infections and, later, higher risks of obesity, asthma, diabetes and SIDS. Mothers also benefit, with a reduced risk of type 2 diabetes, breast cancer, obesity, ovarian cancer, post-partum depression and bladder infections.
As for formula-feeding mothers, as a result of brand loyalty developed after receiving hospital samples of expensive brands from mega-corporations such as Abbott, Mead Johnson and Nestle, they spend an additional $700 a year on formula, on average, than mothers who buy less expensive brands.
The CDC weighs in here.