Breastfed babies are more likely to be right handed

By Dr. Ananya Mandal, MDJan 8 2019

Babies who are breast fed for a longer duration are more likely to be right handed finds a new study. The study titled, 'Breastfeeding and handedness: a systematic review and meta-analysis of individual participant data', by Philippe P. Hujoel of the University of Washington is published in the journal Laterality: Asymmetries of Body, Brain and Cognition.

Newborn baby being breastfed, study on breastfeeding and handedness. Image Credit: Lumen Photos / Shutterstock

Hujoel noted that children who were bottle fed were more likely to develop their left hands as their dominant hands. While children who had been breast fed for nine months or more had a greater prevalence of right handedness. The reason the researcher says could be in the dominant side of the brain that controls the hand. Hujoel, a dentistry professor at the UW School of Public Health said, “We think breastfeeding optimises the process the brain undergoes when solidifying handedness... That's important because it provides an independent line of evidence that breastfeeding may need to last six to nine months.”

The study looked at 62,129 mother-child pairs from five nations (including United States, United Kingdom and Ireland) for this study and found that breastfeeding could be classified as;

• For less than one month
• For one to six months
• For more than six months

The research found that babies who breast fed for less than one month had a 9 percent decreased chance of left handedness compared to bottle fed babies. This was raised to 15 and 22 percent respectively among babies who were breast fed for one to six months and over six months respectively. Breastfeeding for more than six months reduced the chances of left handedness from 13 to 10 percent, they found.

The author writes, “Breastfeeding for more than 6 months, when compared to bottle feeding, was associated with an absolute 3 per cent decreased prevalence for nonrighthandedness, from 13 per cent to 10 per cent, respectively. Twenty-two percent, or about one in five cases of non-righthandedness among bottle-fed infants may thus be attributable to a lack of breast feeding for more than 6 months.”

Hujoel emphasised that the study does not say that breast feeding can lead to right handedness. He explained that handedness is predominantly set while the baby is still within the womb and is influenced by genetics. He said that the reasons behind these findings could be the nutritional content of breast milk and formula that could be influencing the hormones of the baby.