It was already known that immune responses to some infant vaccine could be different according to the type of infant feeding. It has now been suggested that breastfed infants are less likely to have a fever after receiving a routine immunization than non-breastfed infants.

The study, “Breastfeeding and Risk for Fever after Immunization,” published in the June print issue of Pediatrics (published online May 17), measured and recorded the temperatures of 450 infants on the evening of a routine vaccination and for the following three days. Fever was reported for 30 (25 percent) infants being exclusively breastfed, 48 (31 percent) partially breastfed, and 94 (53 percent) of infants not breastfed at all.

Even after taking several confounders into account, including maternal smoking and education, the number of other children in the household, and vaccine dose, researchers still noted a significant difference in the risk of fever. Human milk is rich in anti-inflammatory substances and this could be a reason for the observed reduced incidence of fever. But fever could also be due to some inflammatory agents which are triggered by poor feeding, which is common when children are sick. As breastfed infants are less likely to have poor feeding, probably because breastfeeding is source of comfort during illness, another reason for which fever is less likely among breastfed infants is that they consume more food when they are sick. Thus, breastfeeding itself and the close contact with the mother, rather than some components of human milk, could explain why fever is less likely among breast fed infants. 

The American Academy of Pediatrics is an organization of 60,000 primary care pediatricians, pediatric medical subspecialists and pediatric surgical specialists dedicated to the health, safety and well-being of infants, children, adolescents and young adults. For more information, visit www.aap.org.