Preschool IQ: Prenatal and Early Developmental Correlates

Abstract

The relationship between intelligence quotient (IQ) at age 4 and a variety of factors related to prenatal course delivery physical and mental development and social environment is examined. Subjects were 26760 white and black children whose mothers had enrolled during pregnancy in the Collaborative Perinatal Project at the National Institute of Neurological Diseases and Stroke. Mean IQs differed by race socioeconomic status and sex; children in the white population had a higher mean IQ than those in the black group especially in the middle and upper socioeconomic status groups. Mean IQs also increased from the lower to the upper socioeconomic status group and girls had slightly higher IQs than boys especially among whites. IQs were also higher among children of mothers with more education and who were married during the prenatal period and of fathers who lived in the home. IQs were lower among children of mothers who were under 20 years of age who had had several prior pregnancies who were older at menarche and who were shorter. Mean IQs were higher for children whose mothers had better prenatal care longer pregnancies heavier placentas deliveries not assisted by forceps and among children with larger height weight and head circumference measurements at 4 8 12 and 48 months. All predictor variables accounted for only 25-28% of the variance in IQ among whites and 15-17% among blacks. Neonatal variables accounted for only an additional 1-2% of the variances while infancy and childhood variables added 4-6%. Additional studies of familial influences on IQ will use the information obtained in this study.