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Breastmilk feeding, brain development, and neurocognitive outcomes | LATCH

Article Review: Breast Milk Feeding, Brain Development, and Neurocognitive Outcomes: A 7-Year Longitudinal Study in Infants Born at Less Than 30 Weeks' Gestation

Author: Tamyra Rae Hoff, RN, MS, NE-BC Research suggests that in healthy full-term infants, breastfeeding is beneficial to neurodevelopmental outcomes. Proposed mechanisms linking breastfeeding to brain development include the specific nutrients in breastmilk, greater sensitivity to the infant by mothers providing milk, and social determinants such as maternal education, financial income, and maternal IQ.

Further, breastmilk is considered the optimal form of nutrition for preterm infants in the NICU. These babies also require fortification to increase calories, fat, protein, and minerals to meet the third-trimester nutrition accretion rate of the fetus in utero. Without human milk fortification, preterm babies cannot achieve appropriate weight gain or meet targeted growth standards.

In 2012, the American Academy of Pediatrics stated that “the potent benefits of human milk are such that all preterm infants should receive human milk. Mother’s own milk, fresh or frozen, should be the primary diet, and it should be fortified appropriately for the infant born weighing less than 1.5 kg.”

To study the impact of breastmilk nutrition on neurodevelopment in preterm infants, researchers in Australia studied a large cohort of babies (n=180) born at less than 30 weeks and weighing less than 1250 grams at birth between the years 2001 and 2003. The results were published in the Journal of Pediatrics in an article entitled “Breast Milk Feeding, Brain Development, and Neurocognitive Outcomes: A 7-Year Longitudinal Study in Infants Born at Less Than 30 Weeks' Gestation.”

The objective of the study was to determine whether breastmilk intake was associated with brain size and neurodevelopmental outcomes. The researchers measured brain volume with magnetic resonance imaging (MRI) at term equivalent and 7 years of age and conducted neurodevelopmental assessments at 2 and 7 years of age. The authors calculated two different measures of breast milk intake: the number of days on which the infant received > 50% of enteral breast milk and the mean daily breast milk intake (mL/kg/d).

After reviewing the medical records and calculating the amount of breastmilk these babies received, the researchers determined the total number of days during which the feeding volume of mother’s milk was greater than 50% of the total intake in the first 28 days of life. Mother’s milk was fortified with bovine-based fortifiers, and no donor milk was used. When mother’s milk was unavailable or the volume was not adequate, the babies were given preterm formula. Brain imaging by MRI was performed at term equivalent (~38 to 40 weeks postmenstrual age) and again at 7 years of age. Neurodevelopmental assessment using the Bayley Scales of Infant Development was done at 2 years adjusted age.

At 7 years of age, the children were tested on a wide range of neurodevelopmental performance indicators, including general intelligence, academic achievement, attention, working memory, language, motor function, and visual acuity. The analysis was adjusted for severity of illness, weight gain, and social risk to account for any covariates. The study findings revealed an association between greater breastmilk intake (more than 50% of feeding volume) during the first 28 days of life and both higher deep-grey-matter volume at term equivalent and better neurodevelopmental outcomes at 7 years of age, with higher IQ and better working memory, math computation ability, and motor function.

This study is significant, since only two other studies have examined the relationship between breastmilk, breastfeeding, and long-term outcomes into school age in the very-low-birth-weight population (less than 1500 grams).

The authors of the current paper suggest that the preterm brain may be more sensitive to the beneficial effects of breastmilk earlier in development, specifically before term, when developmental processes such as dendritic and axonal growth and synaptogenesis are ongoing and distinct from the processes that predominate after term, such as pruning and myelination. More studies are needed in this population to validate the emerging evidence that breastmilk has a positive impact on the developing preterm brain.

References:

  1. American Academy of Pediatrics. Breastfeeding and the use of human milk. Section on breastfeeding. Pediatrics. 2012;129(3):e827-e841. doi:10.1542/peds.2011-3552
  2. Belfort MB, Anderson PJ, Nowak, VA, et al. Breast milk feeding, brain development, and neurocognitive outcomes: a 7-year longitudinal study in infants born at less than 30 weeks' gestation. J Pediatr. 2016;177:133-139. doi:10.1016/j.jpeds.2016.06.045