Pune Low Birth Weight Study - Birth to Adulthood - Cognitive Development

Objective: To assess the cognitive development of non-handicapped low birth weight (LBW) infants at 18 years.

Design: Prospective cohort study.

Setting: 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.

Methods: The intelligence quotient (IQ) was determined by Ravens progressive matrices. Assessment of adjustment and aptitude was done.

Results: 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.

Conclusion: 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.