1. A higher dose of maternal milk during the critical period from very preterm birth to term-equivalent age was associated with improved cognitive and academic outcomes and fewer ADHD symptoms at school age
2. These associations were stronger for infants born before 30 weeks, suggesting that infants who are less mature at birth may derive greater benefit from maternal milk feeding after birth
Evidence Rating Level: 2 (Good)
Study Rundown: Findings from studies of full-term infants suggest that prolonged and exclusive breastfeeding in infancy is associated with improved neurodevelopmental outcomes in childhood and later life. These results are not directly generalizable to very preterm populations. This prospective cohort study aimed to examine the extent to which maternal milk feeding after very preterm birth is associated with cognitive, academic, and behavioural outcomes at school age. A total of 586 Australian infants born at less than 33 weeks gestation were included and evaluated at 7 years of age. The exposures were maternal milk dose and duration. Neurodevelopmental outcomes measures at 7 years of age were IQ, academic achievement, symptoms of attention-deficit/hyperactivity disorder (ADHD), executive function, and behaviour. It was found that maternal milk intake during neonatal hospitalization was associated with higher performance IQ, reading and math scores, and fewer ADHD symptoms. Longer duration of maternal milk intake was associated with higher reading, spelling, and math scores. Maternal milk was not associated with improved full-scale IQ, verbal IQ, executive function, or behaviour. Most associations were stronger among infants born at lower gestational ages, particularly less than 30 weeks. These findings reaffirm existing recommendations that breast milk should be the primary diet for infants born very preterm. An effort should be made to create policies and programming that promote and support lactation practices, particularly for women who delivery very preterm infants.
In-Depth [Prospective Cohort Study]: This study performed a secondary analysis of data from the Docosahexaenoic Acid for Improvement of Neurodevelopmental Outcome (DINO) randomized clinical trial. A total of 657 infants born at less than 33 weeks gestation from 5 Australian perinatal centers were enrolled from January 1, 2001 to December 31, 2005. After several exclusions, 586 participants’ baseline and 7-year follow-up data was available for analysis. Study exposures included maternal milk dose, calculated as milliliters per kilogram daily fed to each infant during his/her entire hospitalization, and maternal milk duration, defined as combined duration of maternal milk intake while in hospital plus duration reported at follow-up visits. The primary outcome measure was general intellectual ability, as assessed by the full-scale IQ of the Wechsler Abbreviated Scale of Intelligence (WASI). Secondary outcome measures included academic achievement in reading, spelling, and math, and behaviour as determined by parent-reported scores on various validated questionnaires. Infants were born at a mean (SD) gestational age of 29.6 (2.3) weeks and birth weight of 1323 (412) g. 314 (53.6%) were male and 387 (66.0%) were from singleton gestations. It was found that a higher intake of maternal milk in the neonatal intensive care unit (NICU) and a longer duration of maternal milk feeding were associated with higher full-scale, verbal, and performance IQ scores. Similarly, higher maternal milk dose and duration were associated with higher reading, spelling, and math scores. These positive associations were stronger among infants born at the lowest gestational ages (i.e., <30 weeks of gestation). There was no association between maternal milk and behaviour or ADHD scores.
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