Bottle-fed babies more likely to be left handed, study claims

Infants who are bottle-fed are more likely to be left handed than those who are breastfed, scientists claim.

The study of about 60,000 mother-infant pairs found that the prevalence of left-handedness is lower among breastfed infants as compared to bottle-fed infants.

The study, published in the journal Laterality: Asymmetries of Body, Brain and Cognition, provide further insight into the development of complex brain functions which ultimately determine the infant's handedness.

"We think breastfeeding optimises the process the brain undergoes when solidifying handedness," said Philippe Hujoel, a professor at University of Washington in the US.

"That's important because it provides an independent line of evidence that breastfeeding may need to last six to nine months," said Hujoel.

The study does not imply, however, that breastfeeding leads to right-handedness, Hujoel said. Handedness, whether it be right- or left-handed, is set early in foetal life and is at least partially determined by genetics.

The research sheds light on when the region of the brain that controls handedness localises to one side of the brain, a process known as brain lateralisation.

Possibly, the research shows, breastfeeding optimises this lateralisation towards becoming right- or left-handed.