A University of Manitoba researcher who co-authored a study on the benefits of breastfeeding in preventing wheezing says she hopes research like hers will help take pressure off individual moms and put the onus on society to support breastfeeding.
"Understanding that longer breastfeeding is important for reducing wheezing in this case, and other benefits in the case of other studies, is something that should be promoted at the policy level in terms of maternity leaves, access to support for breastfeeding, sort of developing a positive culture for breastfeeding," said Meghan Azad.
Azad is an assistant professor at the University of Manitoba and a research scientist at the Children's Hospital Research Institute of Manitoba.
"These are all things that are, I would say, responsibilities of the policy makers and our governments and our society as a whole, as opposed to just putting all the pressure on individual moms, because that can be really stressful," she said.
Azad's study, which was published Tuesday in the European Respiratory Journal, followed more than 2,700 Canadian babies and moms from birth to age one as part of the Canadian Healthy Infant Longitudinal Development, or CHILD, Study.
The study found that the longer and more exclusively babies were breastfed, the lower their risk of wheezing — a high-pitched sound indicating difficulty breathing linked to asthma. The effect was especially strong in babies who were at higher risk because their mother had asthma, the study found.
For those higher risk babies who were exclusively breastfed for six months, the rate of wheezing dropped by 62 per cent compared to babies who weren't breastfed at all.
For babies whose moms didn't have asthma, the drop was 26 per cent — "still a protection," but not as strong, Azad said.
Babies who were only partially breastfed got benefits, too, Azad said, although they were undercut by the addition of formula.
However, the early introduction of regular food — as opposed to formula — didn't have the same negative effect.
Research could help moms who can't breastfeed, too
Azad said it's still not clear why her team found the results they did, but they're already working to figure that out.
So far, Azad said there are at least two possibilities already on the table. The first is that breastfeeding is a form of physical exercise for the lungs of babies.
"There has been research looking at how hard a baby has to suck on a breast versus a bottle, and it's a stronger sucking that's required for breastfeeding," she said.
"So this is thought to be kind of exercise that trains the lungs of these babies to grow up strong, and so if you remove the breastfeeding then the lungs don't get this exercise."
The other possibility is that there's something about breast milk itself that's protecting babies from wheezing.
Azad said breast milk contains a number of nutrients like fats, proteins, carbs, vitamins and minerals that are mirrored in formula. But breast milk also provides important extras like enzymes, antibodies and live probiotic bacteria that boost the immune system and help shape the microbiome — that is, the set of bacteria living in and on individual people.
Azad said it's important to sort that out so the information can be used to help moms who can't breastfeed, or can't breastfeed for very long.
Recommendations from the World Health Organization suggest moms should breastfeed exclusively for the first six months of their child's life, and Azad's study found increased benefits when moms breastfed even longer. But that's not possible for all moms, Azad said, for reasons ranging from needing to go back to work to difficulties breastfeeding.
"This research can benefit all babies, because the more we know about breast milk and how it works, the better we can make our infant formulas, which are necessary as an alternative for moms who can't breastfeed," she said.
"The more we know about sort of the optimal feeding for infants, the better we can design nutrition guidelines and infant formulas."