The well-documented health benefits of breastfeeding can last long after you wean your baby.
New research says that just two additional months of nursing can significantly reduce respiratory illnesses for at least two years.
Specifically, the new study found that babies breast-fed for an average of six months had a fivefold decrease in the chances of contracting pneumonia over two years, compared to those just breast-fed an average of four months. Also, the risk of developing recurrent ear infections was halved.
The study's authors say this is the first research showing that just two months of additional breast-feeding could make such a big difference in respiratory health.
"There have been studies showing that six months as opposed to four months can help protect against gastrointestinal infection, but there haven't been any that have demonstrated increased protection against these respiratory illnesses," says study author Dr. Caroline Chantry, an assistant professor of pediatrics at the University of California, Davis, School of Medicine.
The findings came from looking at 2,277 children between the ages of 6 months and 24 months. The babies were divided into five groups: formula-fed only, full breast-feeding for less than one month, full breast-feeding from one to four months, full breast-feeding from four to less than six months, and full breast-feeding for six months or more.
Chantry says most of the babies in the four-to-less-than-six-month group had been breast-fed for around four months and most in the six-or-more-month group had been breast-fed for about six months.
The researchers then tallied the percentages of children in each group who experienced pneumonia, wheezing and recurrent colds or ear infections. The figures were adjusted for factors such as age, birth weight, ethnicity, poverty, two-parent households, parental education, family size, child care, and prenatal smoke exposure.
The results showed significantly lower risks for respiratory infections for the first two years of life among those in the six-month group than those breast-fed for just four months.
The findings are being presented today at the annual joint meeting of the Pediatric Academic Societies and American Academy of Pediatrics in Baltimore.
Chantry says of particular importance is that the babies had been fully breast-fed, meaning they got only breast milk with the exception of some food and/or formula on a less-than-daily basis.
"There have been studies showing that full breast-feeding does have benefits, whereas just once or twice a day doesn't appear to have any measurable benefits," says Chantry. "So the more you breast-feed and how long are clearly important factors."
So what is it about breast milk have that makes it so beneficial?
According to Dr. Lawrence M. Gartner, chairman of the committee on breast-feeding at the American Academy of Pediatrics, it's a complex mix of protective components that simply cannot -- and likely never will be -- duplicated.
"There are thousands of protective components interacting in breast milk," he says, including white blood cells and antibodies. "There are carbohydrates mixed with proteins that block the attachment of bacteria and viruses to the intestine and mucosa of the baby, so even if they get infections, the breast milk will prevent the infection from penetrating through [the] intestine and infecting the baby," he says.
"And the longer the baby is breast-fed, the longer the baby is getting this huge number of protective components," Gartner says.
Breast milk has also been shown to activate the immune system, to increase responsiveness to vaccines, reduce allergies and even reduce the risk for meningitis, according to the academy.