Breastfeeding protects against asthma up to six years of age

Research by the University of Otago in Christchurch and Wellington has shown that breastfeeding of infants has a clear protective effect against children developing asthma or wheezing up to six years of age.

There has long been debate over this issue in the scientific literature, but this latest study of 1105 infants in Christchurch and Wellington over six years demonstrates that exclusive, or indeed any breastfeeding, has a protective effect on the development of asthma in young children.

The study team asked questions about breastfeeding and gathered information on wheezing and asthma in the children at 2, 3, 4, 5 and 6 years.

The protective effect against the development of asthma is even stronger in those infants and children who are atopic, that is those who have allergies and are therefore more vulnerable.

Exclusive breastfeeding for three months within this atopic sub-group reduced current asthma at six years by 59%, bringing their risk down to that of non-atopic children.

“These are very robust and convincing results which support a global public health message to breastfeed to prevent asthma,” says lead author Dr Karen Silvers from the University of Otago, Christchurch.

“If every infant in this NZ cohort had been exclusively breast fed for six months, as is recommended by the WHO, current asthma would have been reduced by 50% at two years, 42% at three, 30% at four, 42% at five and 32% at six years.”

She says the evidence is particularly strong for exclusive breastfeeding in infancy as being protective against asthma.

The study shows a waning of the impact of breastfeeding after four years of age, which Silvers says is to be expected as children are exposed to other risk factors for asthma and wheezing as they age. However, the fact that exclusive breastfeeding protects well beyond the exclusive breastfeeding period (introduction of foods or other drinks) is remarkable.

Dr Silvers says overall this study is further convincing evidence of the known benefits of breastfeeding for mother and child.

The study has been published in The Journal of Paediatrics and was funded by: the Health Research Council, Child Health Research Foundation, Canterbury Medical Research Foundation, Asthma Research Foundation and the David and Cassie Anderson Bequest.