Breast-fed babies less likely to develop behaviour problems

10^th May 2011 - Babies who are breast-fed are far less likely to become children with behaviour problems by the time they reach the age of five than those who receive formula milk, according to a UK study.

Researchers from the universities of Oxford, Essex and York, as well as University College London, say that after adjusting for other factors, the offspring of mothers who breast-fed their child for the first four months were around 30% less likely to develop behaviour problems than those who were only fed formula milk.

Midwives are cautioning that other factors could be responsible for the discrepancy and that the importance of good parenting should not be disregarded.

Writing in the Archives of Disease in Childhood, the study authors say previous small investigations have found that formula-fed children tend to have more behavioural problems, but that once factors such as family background are taken into account the link often diminishes or disappears altogether.

Co-author Maria Quigley, Reader in Statistical Epidemiology at Oxford University, tells us: "There have been a few other large studies and one found an association like ours and another one found no association at all."

Screening out other factors

Quigley says not only is the latest research based on a large number of mothers and children, but they have screened against a number of socio-economic factors that could have influenced the results.

The researchers used data from the UK's Millennium Cohort Study involving 10,037 mother-child pairs. All the infants came from a white ethnic background and were born in a 12 month period in 2000-2001. Most of the mothers (9,525) had given birth at term, with 512 having premature babies.

Mothers taking part were interviewed when their child was nine months old and they were revisited at two-yearly intervals. They completed a Strengths and Differences Questionnaire to establish whether their child had traits such as clinginess, anxiety and hyperactivity, and whether they were prone to lie or steal.

Significant differences

Quigley says the initial statistics showed a large difference in behaviour by the time children reached the age of five between the breast-fed and the formula-fed groups. "We found that for those breast-fed for four months, about 6% had behavioural problems compared with 16% in those that were never breast-fed," she says.

A significant difference remained after the researchers screened for socio-economic factors. "When we did that, there was still about a 30% lower risk of behavioural problems in those who were breast-fed for at least four months," Quigley says.

The authors also note that infants who were born full term and breast-fed for at least four months were at less risk of developing behaviour problems than those who were born premature and fed in the same way. However, they say the evidence for this association remains unclear.