Children exclusively breastfed for longer as infants are less likely to have conduct disorders at primary school-going age.

This is according to a new study published in the medical journal PLOS Medicine.

An international team led by Dr Ruth M Bland at the Africa Centre for Population Health assessed more than 1 500 children in South Africa between 2012 and 2014, 900 of whom had been involved in an early infant feeding study. The children were born to both HIV-negative and HIV-positive mothers.

The study found the longer duration of exclusive breastfeeding was strongly associated with fewer conduct disorders at ages seven to 11.

Children exclusively breastfed for the recommended six months, compared with those exclusively breastfed for less than one month, were approximately half (56 percent) as likely to have conduct disorders at primary school age.

There was weaker evidence that, for boys, exclusive breastfeeding for more than one month improved cognitive development.

“The duration of exclusive breastfeeding of an infant has greater importance than realised in several areas of development,” said lead author Dr Tamsen J Rochat of the Human Science Research Council.

“For example, childhood- onset conduct disorders can lead to aggressive or disruptive behaviours, which interfere with learning and peer relationships, leading to low self-esteem and further behavioural problems.

“Conduct disorders that start in childhood and persist into the teen years are associated with an increase in antisocial behaviours,” she said.