A great example of the imperfection of science is the ongoing debate over the effect of breastfeeding on the risk for allergic disease, especially asthma. While some studies show a positive effect, others show a negative effect or none at all.

In an effort to add to the body of evidence, a group of Finnish researchers conducted a population-based cohort study to assess the effect of breastfeeding on the development of asthma.

Children born in the city of Espoo between January 1, 1984 and December 31, 1989 were asked to participate. The cohort consisted of 2568 children ages 1 to 7 years or 80 percent of the eligible children. Parents or guardians were asked to complete a questionaire. A 6-year follow-up survey was conducted in March, 1997 with families of 1984 children or 77 percent of the the original cohort completing questionaires.

Information on breastfeeding duration and exclusivity was obtained along with age, gender, parent’s education, whether single parent or guardian, exposure to environmental tobacco smoke (mother during pregnancy and/or someone inside the home), parental history of allergic disease, presence of hairy or feathery pets in the home, and type of child care.

Breastfeeding duration was categorized as 0-3 months, 4-6 months, 7-9 months, 10-12 months and 12 months or longer. The optimal period of breastfeeding duration resulting in the lowest risk for asthma was reportedly 7 months and 9 months for chronic respiratory disease (wheezing, cough, and phlegm). Based on this data, the authors concluded that some (breastfeeding) is better than none but more is not necessarily better than less.

Even though the children were followed prospectively, it is important to note that the duration data was obtained retrospectively (children ranged in age from 1 to 7 years). Also there is no reported data regarding exclusivity, a factor thought my many to play a role in the development of allergic disease.

The authors acknowledge that, “Our results suggest a U-shaped relation, but do not exclude the possibility that different mechanisms of selection or confounding influence the results.”

The take-home message—more research is needed. Sound familiar?

In the meantime, what are parents to do? Until more and better data are available, the best advice is to breastfeed exclusively for the first six months at which point most babies will start to show an interest in solid foods. And continue to breastfeed for the first year and beyond for as long as mom, baby, and dad wish.

also on baby gooroo®

Breastfeeding May Not Protect Against Asthma and Allergy

Food Allergy: The Billion Dollar Disease