Risky or higher alcohol consumption while breastfeeding could be associated with poorer cognitive outcomes in children, according to a longitudinal cohort study.

Mother breastfeeding her baby. ©Maxim Tupikov/iStockphoto.com

In a paper published in Pediatrics, researchers analyzed data from 5,107 infants who were followed up every 2 years from Growing Up in Australia: The Longitudinal Study of Australian Children. They also examined other factors, such as information on mothers’ smoking and drinking habits during breastfeeding.

The analysis showed a significant association between increased maternal alcohol consumption and decreased nonverbal reasoning scores in children aged 6-7 years who had been breastfed at any time (95% confidence interval, –0.18 to –0.04; P = .01). The effect was independent of other factors that might have played a role, including prenatal alcohol consumption, maternal age, income, birth weight, head injury, and learning delay.

A comparable association was not seen in children who were never breastfed (95% CI, –0.20 to 0.17; P = .87), which the authors said supported the suggestion that the cognitive effects were the result of alcohol exposure through breast milk.

“This suggests that alcohol exposure through breast milk was responsible for cognitive reductions in breastfed infants rather than psychosocial or environmental factors surrounding maternal alcohol consumption,” wrote Louisa Gibson and Melanie Porter, PhD, of the department of psychology at Macquarie University in Sydney.

However, the association was no longer evident in children aged 8-11 years. The authors said that finding might be attributable to mediation by factors such as increased education.

In addition, Ms. Gibson and Dr. Porter did not find an association between smoking during breastfeeding and cognitive outcomes of the offspring.

The findings on breastfeeding and cognitive reductions in breastfed infants are consistent with animal studies showing that ethanol in breast milk can affect normal brain development.

“Increased cerebral cortex apoptosis and necrosis, for example, may disrupt higher order executive skills relied on in reasoning tasks,” the authors wrote. “Likewise, decreased myelination‍ could reduce the processing speed needed to problem solve quickly.”

Children also might experience reduced cognition as a secondary effect of changes in feeding, nutritional intake, and sleep patterns that could themselves affect brain development, leading to behavioral changes that might “reduce exposure to enriching stimuli.”

However, the authors noted that the frequency and quantity of milk consumed, and the timing of alcohol consumption relative to breastfeeding, were not recorded as part of the study.

“The impact of this is unknown, however, because not all women time their alcohol consumption to limit alcohol exposure, and unpredictable infant feeding patterns can interfere with timing attempts.”

Ms. Gibson and Dr. Porter reported no external funding and no conflicts of interest.

SOURCE: Gibson L et al. Pediatrics 2018 Jul 30. doi: 10.1542/peds.2017-4266.