Breastfeeding Protects Against Asthma

by Heidi Green
June 29, 2012

An estimated 22 million Americans are living with asthma. It is the most common chronic illness in children, one with potentially fatal consequences. According to the American Academy of Pediatrics (AAP), 10–15 percent of U.S. schoolchildren have or have had asthma and the incidence continues to increase. Although asthma symptoms can present at any age, the vast majority of childhood cases (between 80 and 90 percent) are diagnosed by the time a child is 4 or 5 years of age. A new study suggests there may be a way for parents to protect their children from asthma, at least until age 6—the age at which some cases (children with no family history of allergic disease) of childhood asthma disappear. The answer is simple: breastfeed your baby.

Research
Researchers formed the New Zealand Asthma and Allergy Cohort Study in 1997 to “investigate risk factors for the development of asthma.” In its latest analysis, the team looked at the role of breastfeeding in protecting against the development of asthma and wheezing in early childhood.

Study participants were enrolled over a four-year period (1997 to 2001). Expectant mothers were recruited by midwives during prenatal care. Mothers provided infant feeding data (exclusive breastfeeding and additional breastfeeding) via questionnaires when their infants were 3, 6, and 15 months old.

Exclusive breastfeeding was defined as the baby taking in only breast milk or water; it ended when the infant received formula, food, or other liquids. Additional breastfeeding was defined as the baby receiving breast milk in addition to formula, food, or other liquids.

Additional information included “current asthma,” “current wheezing,” and “parental history of allergy.” Skin prick tests identified presence of atopy (skin reaction to allergens) in study infants, looking at a dozen common allergens, including pollen, pets, and foods.

A total of 1,105 children were enrolled in the study. Complete data were available for 892 participants (80.7 percent).

Results
Researchers found that breastfeeding, particularly exclusive breastfeeding, protected against asthma up to 6 years of age. Children who had been exclusively breastfed had a lower risk of asthma, at all ages. The effect was dose-dependent; that is, longer exclusive breastfeeding provided more protection. The researchers explain: “Each month of exclusive breastfeeding reduced the risk of current asthma by 17 percent at 3 years, by 11 percent at 4 years, by 12 percent at 5 years, and by 9 percent at 6 years.”

Although the effect was strongest with exclusive breastfeeding, any breastfeeding was also beneficial. “Current asthma,” the study authors write, “was reduced by 6 percent at 2 years, 6 percent at 3 years, and 4 percent at 4 years for each month of any breastfeeding.” Here too, the longer the breastfeeding, the greater the benefit.

Although researchers saw no relationship between breastfeeding and atopy (genetically predetermined allergy), they did find that exclusive breastfeeding provided more protection against asthma in atopic children (those with a family history of allergic disease). Children with atopy are typically at higher risk for asthma than non-atopic children, but when children with atopy were exclusively breastfed for at least three months, their risk for asthma was no higher than their peers.

If every infant in the study had been exclusively breastfed for six months (in accord with recommendations of the World Health Organization and the American Academy of Pediatrics), the authors theorize that asthma rates would have been reduced be a whopping 50 percent at 2 years of age, 42 percent at 3 years of age, 30 percent at 4 years, 42 percent at 5 years, and 32 percent at 6 years of age.

Recommendations
If there’s one takeaway from this study, it’s this: Breastfeed your baby.

• Breastfeed exclusively for as long as you can—the American Academy of Pediatrics and other leading health authorities recommend exclusive breastfeeding until the introduction of complementary foods at about 6 months of age.
• Continue breastfeeding thereafter—in addition to other foods, drinks, or infant formula—for as long as mother and baby wish to nurse.

Unfortunately, the causes of asthma are unknown. Genetics and environmental factors play a role but sometimes asthma symptoms occur in children for no apparent reason. Except in cases where family history shows a pattern of allergies, parents cannot predict whether their child will be prone to developing allergies or asthma. Aside from avoiding asthma triggers in affected children, there are no proven prevention strategies. Until now.