By Louise Wideroff, Ph.D.
The benefits of breast milk for the developing immune system are widely incorporated into health messages to encourage breast feeding, but is there more to the story? Could breast milk also contain nutrients or other factors that stimulate lasting neurodevelopmental benefits even for premature infants? A group of investigators studied the association of breast milk intake with long term neurodevelopmental outcomes in 180 Australian infants born at <30 weeks gestation or <1250 grams birth weight, and examined 7 years later. Infants with congenital anomalies affecting brain development or function were ineligible to participate. Using medical records, the researchers estimated the number of days infants received >50% of feeding from maternal breast milk during their first 28 days of life.
Small, significant academic benefits at age 7 for breastfed babies
MRIs were done at the term equivalent point (i.e., the predicted birth date) and also at age 7 years to assess various markers of brain volume. At term equivalent age, there was a significant increase in deep nuclear gray matter volume of 0.15 cc/d (95% C.I., 0.2 – 0.20 cc/d) for each additional day of >50% breast milk intake. The statistical model adjusted for differences in term equivalent age, sex, gestational age at birth, social risk score, neonatal illness, and neonatal weight gain. Seven years later, significant brain volume differences were not found however. Researchers also performed neurocognitive tests at age 7, finding small but statistically significant incremental increases in IQ, academic achievement, working memory, and motor function associated with longer predominant breast feeding. Strengths of this study include the 7 year follow up and combination of structural imaging and neurocognitive testing data. Limitations include small sample size and unknown duration of breast milk intake after 28 days. Also, neurocognitive test results may differ by parental education and maternal sensitivity, potentially confounding the results.
Many implications to consider before widespread implementation
What are the social implications of this study? The established benefits of breast milk already make it widely recommended by health care providers for both term and pre-term infants. Health messages should be evidence-based though, and further data would be needed to support the inclusion of neurodevelopmental outcomes. Nevertheless, many women may not breastfeed due to work conditions, illness or personal preference. In some places, donor milk is available for high risk infants through milk banks, where donor screening and proper storage can help minimize transmission of infectious and toxic agents. Online sales in the U.S. are not regulated and safety is a concern. In global health settings, breastfeeding by relatives or wet nurses is a simpler option, although with similar safety concerns. Interestingly, in 2014, the USDA approved commercial sale of breast milk in grocery stores, although its cost remains high and availability limited. Controversies, such as companies purchasing breast milk from economically disadvantaged women, and marketing breast milk to adults as a health food, have occasionally been reported. The viability of this option remains an open question.
Read the original article: Belfort, M.B., Anderson, P.J., Nowak, V.A., Lee, K.J., Molesworth, C., Thompson, D.K., Doyle, L.W., & Inder, T.E. (2016). Breast milk feeding, brain development, and neurocognitive outcomes: A 7-year longitudinal study in infants born at less than 30 weeks’ gestation. Journal of Pediatrics, 177, 133-139.e1. DOI: 10.1016/j.jpeds.2016.06.045
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