Breastfeeding Does Not Protect Against Asthma, Allergies, New Study Shows

Dr. Kramer -- James McGill Professor of Pediatrics, Epidemiology and Biostatistics at McGill University and Scientific Director of CIHR's Institute of Human Development, Child and Youth Health -- and his colleagues followed 13,889 children who had been selected at birth from 31 Belarussian maternity hospitals in the randomized Promotion of the Breastfeeding Intervention Trial (PROBIT). The follow-up took place from December 2002 to April 2005, when the children were 6½ years old.

In the survey, a control group of maternity hospitals and affiliated polyclinics was randomized to continue their traditional practices, while those in the experimental group were trained to teach better breastfeeding techniques and to encourage mothers to breastfeed as long and as exclusively as possible. At the end of the trial, the researchers concluded that breastfeeding does not provide any protection against asthma or allergies. "We found, not only was there no protective effect," said Dr. Kramer, "but the results even suggested an increased risk of positive allergic skin tests."

The results indicate that increased breastfeeding did not reduce the risk of asthma, hayfever or eczema at 6.5 years of age despite large increases in the duration and exclusivity of breastfeeding. It also did not succeed in reducing the prevalence of positive skin prick tests.

PROBIT was led by Dr. Kramer in collaboration with Drs. Robert Platt and Bruce Mazer of McGill and colleagues from the Belarussian Maternal and Child Health Research Institute. The study was conducted in Belarussian maternity hospitals because the former Soviet republic had not yet adopted many of the so-called "baby-friendly" innovations now common in most western countries. "At the time we began this trial in the mid-1990's, the former Soviet countries still had very rigid rules, like the maternity services offered here 30 years ago," explained Kramer. "In a western country, we just wouldn't have been able to make a large difference between the control and the experimental groups."

"Belarus, like most former Soviet and other Eastern European countries, has much lower rates of allergy and asthma than places like Canada, and there's considerable debate as to why that is." explained Dr. Kramer. "However, our results are similar to those found in non-randomized cohort studies in New Zealand, where allergy and asthma are even more common than they are in Canada. This suggests that there is nothing unusual about the setting that would explain our results."

Dr. Kramer remained positive about the benefits of breastfeeding. "In the first phase of our project, we observed reductions in gastrointestinal infections and atopic eczema for the first year of life. I urge mothers to continue to breastfeed."