Adding to reports that breast-feeding boosts brain health, a new study finds that infants breast-fed for six months or longer, especially boys, do considerably better in school at age 10 compared to bottle-fed tots, according to a new study.
''Breast-feeding should be promoted for both boys and girls for its positive benefits," said study leader Wendy Oddy, a researcher at the Telethon Institute for Child Health Research in Perth, Australia.
For the study, published in Pediatrics, she and her colleagues looked at the academic scores at age 10 of more than a thousand children whose mothers had enrolled in an ongoing study in western Australia.
After adjusting for such factors as gender, family income, maternal factors and early stimulation at home, such as reading to children, they estimated the links between breast-feeding and educational outcomes.
Breast-fed babies smarter
Babies who were mainly breast-fed for six months or longer had higher academic scores on standardised tests than those breast-fed fewer than six months, she found.
But the outcome varied by gender, and the improvements were only significant from a statistical point of view for the boys. The boys had better scores in math, reading, spelling and writing if they were breast-fed six months or longer.
Girls breast-fed for six months or longer had a small but statistically insignificant benefit in reading scores.
The reason for the gender differences is unclear, but Oddy speculates that the protective role of breast milk on the brain and its later consequences for language development may have greater benefits for boys because they are more vulnerable during critical development periods.
Another possibility has to do with the positive effect of breast-feeding on the mother-child relationship, she said. "A number of studies found that boys are more reliant than girls on maternal attention and encouragement for the acquisition of cognitive and language skills. If breast-feeding facilitates mother-child interactions, then we would expect the positive effects of this bond to be greater in males compared with females, as we observed."
The researchers tried to account for the mothers' education in their assessment.
Breast milk best in the long term
"We took into account mom's education and family income because we have seen before in other studies that mothers who are better educated tend to breast-feed for longer, and also read and look at books more often with their children," Oddy explained. "We took these factors into account in the analysis so as not to skew the results - and babies breast-fed for longer still did better in terms of their educational scores at 10 years of age."
It's been long understood that breast milk is of great value to infant neurological development. "Nutrients in breast milk that are essential for optimum brain growth, such as long-chain polyunsaturated fatty acids, may not be in formula milk," the researchers noted.
The new data should not discourage mothers of daughters from breast-feeding, added Dr. Ruth Lawrence, director of the Breast-feeding and Human Lactation Study Center at the University of Rochester School of Medicine in New York.
"Because we know the constituents of human milk are so important for brain development, I would not be the least bit discouraged [about] breast-feeding a girl by such data," said Lawrence, also a member of the advisory council of La Leche League International, a breast-feeding advocacy group.
Earlier this year, Oddy published a study suggesting that infants who were breast-fed longer than six months were less likely to have mental health problems as teenagers.
This new study ''adds to growing evidence that breast-feeding for at least six months has beneficial effects on optimal child development," the researchers wrote. "Mothers should be encouraged to breast-feed for six months and beyond."
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