MONDAY, Nov. 13, 2017 (HealthDay News) -- Encouraging new mothers to stick with breast-feeding may halve the already small risk that infants will develop eczema when they hit their teens, new research suggests.
And while the study also found no impact on teenage asthma risk, at least one U.S. pediatrician said other studies have supported the role of breast-feeding in potentially cutting a child's risk of developing allergies or asthma.
The new findings stem from an ongoing investigation tracking some of the protective benefits of breast-feeding among infants reared in the eastern European country of Belarus.
The study didn't compare mothers who did not breast-feed with those who did, and it didn't prove a cause-and-effect link between prolonged breast-feeding and eczema or asthma risk.
Rather, researchers looked at how infants fared down the road when mothers participated in a program that encouraged breast-feeding for as long as possible, compared with otherwise healthy infants reared by mothers not enrolled in such a program.
The result: 0.7 percent of infants whose moms did not receive breast-feeding support ended up developing eczema when they were 16, compared with just 0.3 percent of those whose moms had received breast-feeding support.
However, the theory that breast-feeding might help to curb asthma risk was not supported by the new study findings.
"There is no good evidence from other studies that breast-feeding protects against asthma, so we were not surprised from that point of view," said study author Dr. Carsten Flohr.
Asked if the results likely end speculation on the asthma front, Flohr said, "You can always do more studies. But we are very unlikely to have another [large study], and it would have to be even bigger to find a very small protective effect, if there is one."
Flohr is the head of the unit for population-based dermatology research with the St. John's Institute of Dermatology and the division of genetics and molecular medicine at King's College London.
The World Health Organization recommends breast-feeding infants for four to six months, to promote resistance to allergies and illness. But prior research on whether breast-feeding may promote lung development and asthma resistance have been inconsistent, the study authors said.
According to the U.S. National Institute of Allergy and Infectious Diseases, eczema is a non-contagious but chronic condition, characterized by dry, itchy skin. About 30 percent of Americans -- mostly children and teens -- develop it at one time or another.
For the study, investigators first recruited more than 13,500 new mothers in Belarus between 1996 and 1997.
All had started breast-feeding their infants at birth. But while half received continual breast-feeding encouragement in hospitals that had adopted a 10-step "baby-friendly" program, the other half did so in a standard-care setting.
The researchers tracked the children's eczema and asthma risk at follow-up exams conducted at the ages of 1 year, 6 years, 11.5 years, and 16 years.
At the latest follow-up, teens were examined for eczema around their eyes, neck, elbows, knees and ankles, and by questionnaire. Asthma incidence was assessed both by lung function tests and by questionnaire.
Eczema risk was notably down among those whose mothers had received breast-feeding encouragement. But no such link was seen with asthma risk, the study authors said.
The findings were published online Nov. 13 in the journal JAMA Pediatrics.
Dr. Jay Lieberman, an assistant professor of pediatrics at the University of Tennessee Health Science Center, said he wasn't surprised by the eczema findings, but questioned the study's reliability.
"The problem is that -- as the authors point out -- you can't randomize patients to breast-feeding or not," he noted.
"Thus, while they tried to control for this, they are really only able to say that the kids of mothers randomized to a breast-feeding promotion tended to have less eczema at 16 years of age," Lieberman said.
"There is little scientific reasoning the authors provide to explain this as well," he said, adding that the findings are "absolutely not" the final word on asthma.
"There are plenty of studies that still support the role of breast-feeding to decrease the likelihood of an infant/child going on to develop allergies or asthma," he said. "If I have a mother who is going to have a child, and they ask me what they can do to decrease their child's chance of having eczema, food allergies, or asthma, I am 100 percent going to tell them to breast-feed."
There's more on breast-feeding at the U.S. National Institute of Child Health and Human Development.
SOURCES: Carsten Flohr, M.D., Ph.D., head, unit for population-based dermatology research, St. John's Institute of Dermatology, division of genetics and molecular medicine, King's College London and Guy's & St. Thomas' National Health Service Foundation Trust, London; Jay Lieberman, M.D., assistant professor, pediatrics, University of Tennessee Health Science Center, Memphis; Nov. 13, 2017, JAMA Pediatrics, online