NEW YORK (Reuters Health) - Children who are breastfed for longer than six months could be at lower risk of mental health problems later in life, new research from Australia suggests.

Danielle Shield breastfeeds her six-month-old daughter Rosa Murphy at the Delta Airlines counter at Logan Airport in Boston, Massachusetts November 21, 2006. REUTERS/Brian Snyder

“Breastfeeding for a longer duration appears to have significant benefits for the onward mental health of the child into adolescence,” Dr. Wendy H. Oddy of the Telethon Institute for Child Health Research in West Perth and her colleagues report in The Journal of Pediatrics.

Breastfeeding could help babies cope better with stress, the researchers note, and may also signal a stronger mother-child attachment and these benefits may last.

Oddy and her colleagues studied 2,366 children born to women enrolled the Western Australia Pregnancy Cohort (Raine) Study. Each of the children underwent a mental health assessment when they were 2, 5, 8, 10, and 14 years old.

Eleven percent were never breastfed, 38 percent were breastfed for less than six months, and just over half were breastfed for six months or longer.

The mothers who breastfed for less than six months were younger, less educated, poorer, and more stressed, and were also more likely to be smokers, than the moms who breastfed for longer. They were also more likely to suffer from postpartum depression, and their babies were more likely to have growth problems.

At each of the assessments, the researchers found, children who were breastfed for shorter periods of time had worse behavior. Differences were seen for internalizing behavior, in which negativity is directed inwards, for example depression; and in externalizing behaviors, such as aggression.

For each additional month a child was breastfed, behavior improved.

Breastfeeding for six months or longer remained positively associated with the mental health and well-being of children and adolescents after the investigators adjusted for social, economic and psychological factors as well as early life events.

They conclude: “Interventions aimed at increasing breastfeeding duration could be of long-term benefit for child and adolescent mental health.”

SOURCE: The Journal of Pediatrics, online December 14, 2009.