Naeye and Peters ( 19x4) investigated the mental development of smokers’ children by comparing siblings whose mothers smoked in one but not in subsequent pregnan-

by comparing siblings whose mothers smoked in one but not in subsequent pregnancies and found that hyperactivity. short attention span, and lower scores on spelling and reading tests were more frequent for the children whose mother had smoked during pregnancy. but the differences were relatively small, the test scores being only 2 to 4 percent lower. Dunn also studied neurological and electroencephalographic abnormalities among 6-year-old children of smokers and found these conditions to be slightly more common in the children of mothers who had smoked during pregnancy, but again the differences were not statistically significant. Small sample sizes in many of these studies and the relative infrequency of the events of interest limit interpretation of the studies (Dunn et al. 1977).