The subjects (N = 50) were born to mothers who had earlier participated in an extensive clinical investigation during their pregnancies. Maternal serum hormone levels were investigated from pregnancy week 20 and on to partus. Fourteen children were born small-for-gestational age (SGA) and eight pre-term appropriate-for-gestational age (AGA). Each SGA child had two control children, born to mothers with normal or high serum levels of alpha-fetoprotein (AFP) in pregnancy week 16-17. Elevated serum levels of AFP was considered to be a sign of fetal stress. All 50 children were administered the WISC-test at 10 years of age. The SGA children had lower scores than control children in Performance and Full scale scores. The pre-term SGA children had lower scores than the controls in Verbal, Performance and Full scales. That was not the case for on-time SGA and pre-term AGA children. Girls born to smoking mothers performed less well than girls of non-smoking mothers on the Verbal scale. Positive correlations of maternal serum hormone levels (oestriol, hCG, and hPL) and WISC-test scores were present for girls. For boys a single maternal hormone in pregnancy (prolactin) was correlated with WISC-test scores at 10 years of age.