Infection rates - including respiratory and urinary infections, ear infections (otitis media), stomach upsets (gastroenteritis), conjunctivitis and thrush - were tracked at the one-, three-, six-, nine- and 12-month marks.
Partial breastfeeding did not have the same protective effects as prolonged exclusive breast-feeding, the study found. And when infection did strike, the illness was typically less severe among children who were exclusively breast-fed (having ingested no substitute formula) in their first six months of life, the study authors stated.
The researchers observed that the longer an infant was breast-fed exclusively, the lower the child's risk for infection. Longer exclusive breast-feeding also appeared to translate into fewer visits to a doctor and fewer infection-related hospital admissions.
The study authors wrote:
"Findings from this large-scale prospective study in a well-defined infant population with adequate healthcare standards suggest that exclusive breastfeeding contributes to protection against common infections during infancy regarding and lessens the frequency and severity of infectious episodes,"
"Partial breastfeeding did not seem to provide this protective effect."
It is thought that breast-feeding is beneficial for babies because of the nutritional and immunological benefits it provides. The antibodies found in mothers' milk help to boost the baby's underdeveloped immune system, protecting it from infections. Breast milk also contains many essential nutrients that are in more absorbable form than those provided in formula milk.
Research paper details: