Preterm infant linear growth and adiposity gain: trade-offs for later weight status and intelligence quotient

Objective: To examine trade-offs between cognitive outcome and overweight/obesity in preterm-born infants at school age and young adulthood in relation to weight gain and linear growth during infancy.

Study design: We studied 945 participants in the Infant Health and Development Program, an 8-center study of preterm (≤37 weeks gestational age), low birth weight (≤2500 g) infants from birth to age 18 years. Adjusting for maternal and child factors in logistic regression, we estimated the odds of overweight/obesity (body mass index [BMI] ≥85th percentile at age 8 or ≥25 kg/m(2) at age 18) and in separate models, low IQ (<85) per z-score changes in infant length and BMI from term to 4 months, from 4 to 12 months, and from 12 to 18 months.

Results: More rapid linear growth from term to 4 months was associated with lower odds of IQ <85 at age 8 years (OR, 0.82; 95% CI, 0.70-0.96), but higher odds of overweight/obesity (OR, 1.27; 95% CI, 1.05-1.53). More rapid BMI gain in all 3 infant time intervals was also associated with higher odds of overweight/obesity, and BMI gain from 4-12 months was associated with lower odds of IQ <85 at age 8. Results at age 18 were similar.

Conclusion: In these preterm, low birth weight infants born in the 1980s, faster linear growth soon after term was associated with better cognition, but also with a greater risk of overweight/obesity at age 8 years and 18 years. BMI gain over the entire 18 months after term was associated with later risk of overweight/obesity, with less evidence of a benefit for IQ.