Maternal cortisol levels (at 15, 19, 25, 31 and 37 weeks' gestation) and fetal movement response to vibroacoustic stimulation (VAS; at 25, 31 and 37 weeks) were assessed in 190 mother-fetus pairs. Fetuses showed a response to the VAS at 25 weeks and there was evidence of increasing maturation in the response at 31 and 37 weeks. Early elevations in cortisol predicted a failure to respond to the VAS at 25 weeks and later elevations in cortisol were associated with a larger response among fetuses when assessed near term. The associations between cortisol and VAS emerged earlier and were more apparent among female fetuses than among the males. The findings provide support for the role of prenatal glucocorticoids in shaping human fetal CNS development. (Contains 4 figures and 2 tables.)