Fetal head circumference (HC) growth was examined prospectively in children with autism spectrum disorder (ASD). ASD participants (N = 14) were each matched with four control participants (N = 56) on a range of parameters known to influence fetal growth. HC was measured using ultrasonography at approximately 18 weeks gestation and again at birth using a paper tape-measure. Overall body size was indexed by fetal femur-length and birth length. There was no between-groups difference in head circumference at either time-point. While a small number of children with ASD had disproportionately large head circumference relative to body size at both time-points, the between-groups difference did not reach statistical significance in this small sample. These preliminary findings suggest that further investigation of fetal growth in ASD is warranted. (Contains 3 tables and 2 figures.)