Early Diet and Later IQ in Preterm Infant Boys
Early Diet and Later IQ in Preterm Infant Boys
ABSTRACT & COMMENTARY
Synopsis: Consumption of a preterm infant formula, designed to meet the calculated needs of preterm infants by enrichment with protein, calories, and micronutrients, was associated with significantly better cognitive performance at 7-8 years of age.
Source: Lucas A, et al. Randomized trial of early diet in preterm babies and later intelligence quotient. BMJ 1998; 317:1481-1487.
In order to determine whether perinatal nutrition influences cognitive function in 7-8-year-old children who were born prematurely, 360 infants who were born prematurely were studied. These infants had been fed either standard premature infant formula or a premature infant formula enriched with protein, calories, and micronutrients. At 7-8 years of age, male infants fed the standard formula had a mean 12.2-point lower verbal IQ score than male infants receiving the enriched formula. This difference was statistically significant (P = 0.01). These differences were not seen in girls. There was also a higher incidence of cerebral palsy in male children who had received the standard premature formula. Lucas and colleagues hypothesize that preterm male infants are vulnerable to suboptimal early nutrition in terms of their cognitive performance—notably language-based skills—at 7-8 years of age, when cognitive skills are highly predictive of adult ones. Cognitive function, notably in males, may be permanently affected by neonatal nutrition.
COMMENT BY RICHARD A. EHRENKRANZ, MD, FAAP
The American Academy of Pediatrics Committee on Nutrition (AAPCON) currently recommends that feedings offered to very low birth weight (VLBW) preterm infants should be "designed to provide nutrients to approximate the rate of growth and composition of weight gain for the normal fetus of the same postconceptional age and to maintain normal concentrations of blood and tissue nutrients."1 It has been widely accepted that the provision of such "optimal nutrition" during the VLBW infant’s hospitalization in the NICU would support his or her later growth and neurodevelopment.
Lucas et al have previously reported that, when compared to preterm infants receiving standard term infant formula, those preterm infants receiving a specialized preterm infant formula that was enriched in protein, energy, and micronutrients had significant improvements in growth and developmental indices at 18 months corrected age.2 The current report extends those observations and describes the results of formal cognitive tests in that same cohort of children at 7-8 years of age. Although there were no significant differences in verbal, performance, or overall IQ scores between infants fed solely standard term formula compared to those fed solely preterm formula or between those fed their own mother’s milk with either standard term formula or preterm formula supplements, a significant interaction between diet and gender was identified. Specifically, a beneficial effect of preterm formula on verbal IQ was seen for boys, but not girls, and was confined to those fed exclusively preterm formula; this difference was not observed between boys receiving their own mother’s milk and either standard term or preterm formula supplements. A similar observation was also noted for the incidence of cerebral palsy; there was a higher incidence of cerebral palsy in boys fed the standard term formula. However, since these beneficial effects were only seen in solely preterm-formula-fed males and since it is unclear why only the male brain would be vulnerable to early nutritional insults, they may only represent chance findings in a subpopulation of the study cohort.
Nonetheless, this report supports the AAPCON’s recommendations about the importance of meeting the nutritional needs of VLBW preterm infants and suggests that early nutrition has a major influence on later cognitive development, especially in males.
References
1. Pediatric Nutrition Handbook, 4th ed. Elk Grove Village, IL: American Academy of Pediatrics;1998: 55.
2. Lucas AA, et al. Lancet 1990;317:1477-1481.
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