Asthmatic mothers encouraged to breastfeed without fear as it boosts baby’s lung power: Study

By Dr. Ananya Mandal, MDFeb 7 2012

According to new research from British scientists, breastfeeding could help babies develop stronger lungs.

In their study published in the American Journal of Respiratory and Critical Care Medicine they looked at nearly 1,500 children from birth to ages eight to 14. Parents provided information on breastfeeding history when their children were 12 months old, and the children had a series of tests to assess lung function between the ages of 8 and 14.

The study found that the longer the children were breastfed, the better they performed on tests measuring lung function. Children whose moms had asthma and were breastfed for four months or longer also performed better in tests measuring lung capacity, suggesting breastfeeding could lower the risk of asthma.

The findings appear to contradict several earlier studies that raised concerns that breast milk may not always be best for babies born to mothers with the respiratory disease. “We found evidence for improvement in some aspects of lung function in children who were breastfed, which was strongest in those whose mothers had asthma,” says researcher Claudia E. Kuehni, of the University of Bern’s Institute of Social and Preventive Medicine in Bern, Switzerland. “This is reassuring for new mothers with asthma,” she says. “Like other mothers, they should be encouraged to breastfeed.”

The evidence as a whole suggests that breastfeeding is beneficial for lung development, even when mom has asthma, says pediatrician Roya Samuels, of Cohen Children’s Medical Center in New Hyde Park, N.Y. She says it is clear that babies who are breastfed tend to be healthier overall, with fewer ear infections, respiratory illnesses, and gastrointestinal problems. “Moms with asthma can absolutely be reassured that breastfeeding will provide significant benefits for their children,” she says.

She says the new study finds no support for the theory that new moms with poorly controlled asthma may expose their babies to hormones through their breast milk that cause inflammation and increase asthma risk. “No research has been able to prove this theory or debunk it, until now,” she says.

“I think the evidence is that breastfeeding increases lung volume, independent of if the mother is asthmatic or not,” said Dr. Wilfried Karmaus, who studies asthma at the University of South Carolina in Columbia and wasn't involved in the new work. “If the lung volume is increased, then you are less susceptible to get asthma,” he told Reuters Health. “It's important even to tell asthmatic mothers to breastfeed their children.”

One limitation of their study, the researchers noted, is that only about one-third of the kids they followed from birth and invited to do lung tests - more than 4,000 in total - actually participated, which could skew the results if certain types of kids were more likely to come in than others.

In yet another study, from New Zealand, a second group of researchers also followed babies from birth, but instead of testing lung function they asked parents of six-year-olds if their kids had ever been diagnosed with asthma or had used an inhaler or wheezed in the last year. With data on more than 1,000 kids, including about 200 with asthma at their last visit, a team led by Karen Silvers found that each month of exclusive breastfeeding (without any formula mixed in) was tied to a nine-percent drop in asthma risk. Silvers, from the University of Otago in Christchurch, and her colleagues reported their findings Sunday in the Journal of Pediatrics.

The World Health Organization recommends breastfeeding exclusively for the first six months of life, continued for two years or longer.

Dr. Theresa Guilbert, a pediatric pulmonologist from the University of Wisconsin School of Medicine and Public Health in Madison, said that despite the new findings, it's still “controversial” whether or not asthmatic moms pass on any risk to their babies by breastfeeding. None of the studies that have been done can prove cause-and-effect one way or the other, she said, and conflicting results might be due to different samples of moms, from areas with different diets and environmental exposures. “There's a lot of things that breastfeeding is very, very good for,” Guilbert, who wasn't involved in the new research, told Reuters Health. “I think the jury's still out on the risk of breastfeeding from mothers that are asthmatic.” However she added, “I don't think any of that (evidence) is now strong enough to tell moms they should stop breastfeeding... because of all the other important benefits that breastfeeding conveys to the child.”