Fetal onset of general movements.

Perinatal qualitative assessment of general movements (GMs) is a tool to evaluate the integrity of the young nervous system. The aim of this investigation was to study the emergence of GMs. Fetal onset of GMs was studied sonographically in 18 fetuses during the first trimester of uncomplicated in vitro fertilization (IVF) pregnancies in weekly assessments. The earliest motility consisting of small and simple sideways bending (SB) of head and/or rump starts at 7 wk, lasting about 1 s. Between 7 and 8.5 wk, motility differentiates further into movements in which also one or two arms or legs become active; movements are still slow, small, and in one direction, but the duration increases to a few seconds. The transition into GMs at 9-10 wk is characterized by variation in participating body parts and amplitude, speed, and direction during longer periods of time. Between 9 and 13 wk, simple and stereotyped SBs and GMs may coexist. At 9 wk, the incidence of SBs decreases (p = 0.01) and that of GMs increases (p = 0.006). The data suggest that initial simple fetal motility is generated by spinal and brainstem circuitries, and the emergence of complex and variable GMs denotes the onset of supraspinal modulation of this spinal and brainstem activity.