Preemies typically have smaller brains than full-term infants
Feeding premature babies mostly breast milk during the first month of life appears to spur more robust brain growth, compared with babies given little or no breast milk.
A study of preterm infants in the Neonatal Intensive Care Unit (NICU) at St. Louis Children’s Hospital found preemies whose daily diets were at least 50 percent breast milk had more brain tissue and cortical-surface area by their due dates than premature babies who consumed lesser amounts of breast milk.
“The brains of babies born before their due dates usually are not fully developed,” said senior investigator Cynthia Rogers, M.D., an assistant professor of child psychiatry at Washington University in St. Louis. “But breast milk has been shown to be helpful in other areas of development, so we looked to see what effect it might have on the brain. With MRI scans, we found that babies fed more breast milk had larger brain volumes. This is important because several other studies have shown a correlation between brain volume and cognitive development.”
In the study of 77 preterm infants, researchers retrospectively looked to see how much breast milk those babies had received while being cared for in the NICU. Then, researchers conducted brain scans on those infants at about the time each would have been born had the babies not been born early. All of the babies were born at least 10 weeks premature, with an average gestation of 26 weeks, or about 14 weeks ahead of schedule. Because they are still developing, preemies typically have smaller brains than full-term infants.
Researchers didn’t distinguish between milk that came from the babies’ own mom and breast milk donated by other women. Instead, they focused on the influence of breast milk in general.
“As the amount of breast milk increased, so did a baby’s chances of having a larger cortical surface area,” said first author Erin Reynolds, a research technician in Dr. Rogers’ laboratory. “The cortex is the part of the brain associated with cognition, so we assume that more cortex will help improve cognition as the babies grow and develop.”
Preterm birth, a leading cause of neurologic problems in children, has been linked to psychiatric disorders later in childhood.
The researchers plan to continue following the babies in the study through their first several years of life to see how they grow, focusing on motor, cognitive and social development. As the babies get older, researchers believe they will be able to determine the effects of early exposure to breast milk on later development.
“We want to see whether this difference in brain size has an effect on any of those developmental milestones,” Dr. Rogers said. “Neonatologists already believe breast milk is the best nutrition for preterm infants. We wanted to see whether it was possible to detect the impact of breast milk on the brain this early in life and whether the benefits appeared quickly or developed over time.”
More study is needed to determine exactly how breast milk affects the brain and what is present in the milk that seems to promote brain development. Dr. Rogers said that because all of the babies in the study were preterm babies, it isn’t clear whether breast milk would provide similar benefits for full-term babies.
Though the rate of preterm babies in the United States has dropped, black women are still more likely to deliver their babies too early.