ABSTRACT
This chapter investigates the combined effects of the pre- and postnatal predictors on IQ, and their relative importance. It uses a forward stepwise multiple regression technique to partial out the overlap in the individual predictor-variable–IQ correlations. The chapter analyzes the amount of variance in IQ accounted for by the predictors in the following three stages in each race-sex sample: prenatal variables only, prenatal and neonatal variables, and all variables including those from infancy and childhood. Number of prenatal visits, maternal age, and marital status made small contributions to variance in IQ. Fourteen of the 42 predictors made significant contributions to IQ variance, including the neonatal variables of brain abnormality, head circumference, and one-minute Apgar score. Maternal age and number of prenatal visits entered in the third and fourth steps, and subsequently there were only very small increases in the multiple correlation between IQ and the prenatal predictors.
