Movements expressed by the embryo or fetus that are not a response to explicit stimulation by an experimenter. At least some spontaneous movements are generated by activity in the central nervous system, although in intact embryos/fetuses movements may be influenced by uncontrolled sources of environmental stimuli or self-stimulation.
See Central pattern generator (CPG), Motility, Movement, Preyer-Tracy hypothesis of autogeneous motility, Self-stimulation