Breastfed babies are better at coping with stress when they're 10 years old than their bottle-fed peers, says a new study. Those who had been given formula were found to be less equipped to handle stressful events such as parental divorce.

The researchers evaluated almost 9,000 children who were part of the 1970 British Cohort Study. They considered birthweight, feeding practices and other relevant factors, such as maternal depression, parents' educational levels, their smoking habits and social class.

The data was gathered at the time of birth and at two five-year intervals from birth attendants, visiting health professionals, parents and teachers.

At five years, the moms in the group were asked whether they had breastfed for any amount of time.

When the children reached 10 years, their teachers were queried concerning anxious behavior in school and mothers were asked if they had gotten divorced in the past five years.

The children who were breastfed were significantly less anxious than those who were bottle fed, the researchers found.

Parental divorce was associated with a spike in anxiety in both groups. However, the breastfed children of divorced parents appeared twice as likely to be highly anxious, while the bottle-fed children of divorce appeared nine times as likely to be highly anxious, based on their teachers' ratings.

Although the researchers controlled for factors other than feeding practices that might have influenced the results, their findings did not change.

Length of breastfeeding did not seem to make a difference in perceived anxiety levels. Those breastfed for less than a month seemed to react to their parents' divorce with the same level of anxiety as those breastfed for more than three months.

Although breastfeeding is known to produce many benefits, including strengthening the mother and child bond, the researchers were at a loss to explain how it might affect childhood stress levels over parental divorce.

They speculated that breastfeeding could be a marker for other lifestyle factors or family traits that might better equip children to handle stress.