Longer durations of exclusive breastfeeding can lead to fewer behavioural disorders in children at the primary school age, finds a new study that focused on how the experiences of a child in his or her first years of life influences later behaviour and abilities.

Conduct or behavioural disorders that typically start in childhood and persist into the teenage years are associated with an increase in antisocial (and potentially violent or criminal) behaviours, poor long-term mental health and low academic achievement in later life.

The findings showed that children who were exclusively breastfed for the recommended first six months were approximately half as likely to have conduct disorders at the ages of 7-11 years, compared with those exclusively breastfed for less than one month.

"The duration of exclusive breastfeeding of an infant has greater importance than previously realised in several areas of development," said lead author Tamsen J. Rochat of the Human Science Research Council, Durban, South Africa.

"Childhood onset conduct disorders can lead to aggressive or disruptive behaviours, which interfere with learning and peer relationships, in turn leading to low self-esteem and further behavioural problems," Rochat added.

Further, children whose mothers had a current mental health problem or severe parenting stress were two-and-a-half times more likely to exhibit emotional-behavioural problems.

For the research, published in PLOS Medicine, the team assessed over 1,500 children in South Africa, 900 of whom had been involved in an early infant feeding study.