Passive and active maternal smoking during pregnancy, as measured by serum cotinine, and postnatal smoke exposure. II. Effects on neurodevelopment at age 5 years.

The authors sought to determine the neurobehavioral effects of prenatal exposure to maternal active smoking and environmental tobacco smoke (ETS), assessed by maternal serum cotinine level, and of postnatal exposure to smoke based on maternal report. Five-year-old children (n = 2,124) who were participants in the Child Health and Development Studies in Oakland, California, between 1964 and 1967 were evaluated with the use of the Peabody Picture Vocabulary Test (PPVT) and the Raven Coloured Progressive Matrices Test, and also assessed on a behavioral rating scale completed by the mother that included questions on activity level. Children of ETS-exposed women did not differ from children of other nonsmokers on neurobehavioral assessment. Children whose mothers smoked during pregnancy had somewhat higher adjusted Raven (p = 0.10) and PPVT scores (p = 0.06) than children of nonsmokers, although they did not differ in their activity level (p = 0.32). However, children smoke-exposed during childhood did have lower adjusted Raven (p = 0.01) and PPVT scores (p = 0.16), and were rated more active by their mothers (p = 0.04). These differences may be attributed to uncontrolled confounding of sociobehavioral variables. However, the authors cannot rule out the possibility that ETS exposure during childhood may be more hazardous to neurodevelopment than prenatal exposure.