Summary: Preterm babies who were fed maternal milk during and after a stay in NICU had greater academic achievement, higher IQs, and reduced risk of ADHD than their preterm peers who were not fed maternal milk.
Source: Bingham and Women’s Hospital
Children who were born preterm are at heightened risk of lower academic achievement in math, reading and other skills and are also at greater risk for attention-deficit/hyperactivity disorder (ADHD).
But a new study suggests that an intervention in the first weeks and months of a preterm infant’s life may lead to better neurodevelopmental outcomes in later years.
In a study that followed preterm infants for seven years, investigators from Brigham and Women’s Hospital together with collaborators at the South Australian Health and Medical Research Institute found that children who received greater quantities of maternal milk both during and after time in the neonatal intensive care unit (NICU) had greater academic achievement, higher IQs and reduced ADHD symptoms.
Results are published in JAMA Network Open.
“Our study finds that there may be long-term neurodevelopmental benefits to providing maternal milk to preterm infants,” said corresponding author Mandy Brown Belfort, MD, MPH, of the Department of Pediatric Newborn Medicine.
“A lot of families are dedicated to the idea of providing maternal milk but may face steep challenges. Our findings emphasize the importance of providing support for initiating and sustaining lactation because maternal milk at this early age can provide benefits years later.”
Belfort and colleagues looked at neurodevelopmental outcomes for 586 infants born at less than 33 weeks’ gestation at one of five Australian perinatal centers. Children were evaluated at age 7 (corrected for prematurity).
The team looked at data on maternal milk dose (volume of maternal milk infants received each day) and maternal milk duration (how long parents continued breastfeeding) predicted several neurodevelopmental outcomes.
These outcomes included academic achievement, Verbal and Performance IQ, symptoms of ADHD, executive function, and behavior.
Overall, the team found that higher maternal milk intake was associated with higher Performance IQ and higher reading and math scores. Parents also reported fewer ADHD symptoms for children who consumed more maternal milk during infancy. Duration of maternal milk intake (up to 18 months corrected age) was also associated with higher reading, spelling and math scores.
The researchers controlled for confounders, including clinical and social factors. These beneficial associations were stronger for infants born at the lowest gestational ages, particularly those born below 30 weeks of gestation.
The authors note that their study is observational — they cannot determine causality as there may be other, unaccounted factors that influence both the ability to provide maternal milk and academic achievement.
The study’s strengths include its large size, the range of outcomes examined, and that the researchers could assess school-age outcomes. Other studies have only followed children through preschool age, making it difficult to assess the full range of neurodevelopmental outcomes.
Overall, Belfort sees the team’s findings as an affirmation of guidance from the American Academy of Pediatrics and World Health Organization, both of which recommend maternal milk for infants.
“Our study confirms recommended strategies for supporting parents to provide maternal milk for preterm infants,” said Belfort. “And it strengthens the call for health policies and parental leave policies that support rather than work against parents. As a society, we need to invest in families — it’s an investment that will continue to benefit children when they reach school age.”
Disclosures: Belfort reported serving on the research advisory board for Mother’s Milk Bank Northeast.
Funding: This work was supported by a grant from the National Health and Medical Research Council (GNT1135155).
This prospective cohort study assessed 586 infants born at less than 33 weeks’ gestation at 5 Australian perinatal centers and enrolled in the Docosahexaenoic Acid for Improvement of Neurodevelopmental Outcomes study (January 1, 2001, to December 31, 2005) who were evaluated at a corrected age of 7 years. The statistical analysis was completed on January 19, 2022.
Maternal milk intake, including mean volume (milliliters per kilogram per day) during neonatal hospitalization and total duration (in months).
Main Outcomes and Measures
Neurodevelopmental outcomes at 7 years of age were (1) IQ (Wechsler Abbreviated Scale of Intelligence), (2) academic achievement (Wide Range Achievement Test, Fourth Edition), (3) symptoms of attention-deficit/hyperactivity disorder (ADHD) (Conners Third Edition ADHD Index, parent reported), (4) executive function (Behavior Rating Inventory of Executive Functioning, parent reported), and (5) behavior (Strengths and Difficulties Questionnaire, parent reported).
A total of 586 infants (mean [SD] gestational age at birth, 29.6 [2.3] weeks; 314 male [53.6%]) born to 486 mothers (mean [SD] age, 30.6 [5.5] years; 447 [92.0%] White) were included.
Mean (SD) maternal milk intake in the neonatal intensive care unit was 99 (48) mL/kg daily, and mean (SD) maternal milk duration was 5.1 (5.4) months. Mean (SD) full-scale IQ was 98.5 (13.3) points.
After covariate adjustment, higher maternal milk intake during the neonatal hospitalization was associated with higher performance IQ (0.67 points per additional 25 mL/kg daily; 95% CI, 0.10-1.23 points), reading scores (1.14 points per 25 mL/kg daily; 95% CI, 0.39-1.89 points), and math scores (0.76 points per 25 mL/kg daily; 95% CI, 0.14-1.37 points) and fewer ADHD symptoms (−1.08 points per 25 mL/kg daily; 95% CI, −1.96 to −0.20 points).
Longer duration of maternal milk intake was associated with higher reading (0.33 points per additional month; 95% CI, 0.03-0.63 points), spelling (0.31 points per month; 95% CI, 0.01-0.62 points), and math (0.30 points per month; 95% CI, 0.03-0.58 points) scores.
Maternal milk was not associated with improved full-scale IQ, verbal IQ, executive function, or behavior. Most associations were stronger among infants born at lower gestational ages, particularly less than 30 weeks (interaction P values <.01).
Conclusions and Relevance
In this cohort study of preterm infants, maternal milk feeding during the neonatal hospitalization and after discharge were associated with better school-age performance IQ and academic achievement and with a reduction in ADHD symptoms, particularly among infants born at less than 30 weeks’ gestation.