In ten growth retarded fetuses (IUGR) a qualitative and quantitative analysis was made of various movement patterns. The results were compared with those of ten matched appropriate-for-gestational age fetuses (AGA). The aim of the study was to see whether malnourished, growth retarded fetuses move differently to well nourished, normal fetuses. The real-time ultrasound recordings were of one hour's duration and the analysis of motility was carried out during replay of video recordings. The qualitative analysis of each separate general movement was performed with 'Gestalt perception' describing the speed, force and amplitude of each movement as well as the variability of these descriptors. Interobserver agreement was evaluated by displaying general movements of both groups to 8 observers. There was an overall interobserver agreement of 89%. The IUGR fetuses moved less, but in individual cases an overlap existed with control fetuses. There was a reduction of both number and duration of general movements in the IUGR group. Furthermore the markedly reduced incidence of startles, twitches and isolated limb movements was striking. The qualitative analysis of general movements revealed a reduction of the quicker components leading to slow and monotonous movement patterns. There was also a marked reduction of variability of speed and intensity within each movement pattern. We speculate that the reduced variability of motor patterns may find its origin in a change of central neural function, just as the reduced heart rate variability and decreased breathing irregularity found in IUGR fetuses.