Pune low birth weight study — Birth to adulthood — Cognitive development

Abstract

To assess the cognitive development of non-handicapped low birth weight (LBW) infants at 18 years. Prospective cohort study. Infants born between 1987 - 1989 with birth weight less than 2000 g and discharged from a neonatal special care unit were followed up till the age of 18 years. The intelligence quotient (IQ) was determined by Ravens progressive matrices. Assessment of adjustment and aptitude was done. The cohort of 161 LBW infants was divided into three groups according to their gestation - preterm SGA (n=61), full term SGA (n=30) and preterm AGA (n=70). 71 full term AGA infants served as controls. The IQ of the study group (Percentile 39.3) was significantly lower than that of controls (Percentile 54.9) (P=0.002). Preterm SGA subjects had the lowest IQ (Percentile 35.5), though just within normal limits. Males from the study group had significantly lower IQ than male controls (P=0.03). The IQ of PTSGA subjects of college educated mothers (P=0.004) and belonging to higher socio-economic class (P=0.04) was significantly higher. On the differential aptitude test, PTSGA subjects were poor in speed and mechanical reasoning. The 18 year IQ could be best predicted by IQ at 6 and 12 years. Preterm SGA children have the lowest IQ at 18 years, males have lower IQ. Maternal education and socio-economic status have great impact on cognitive development. Good prediction of the 18 year IQ can be done by the 6 and 12 year IQ.