Preterm to early postterm changes in the development of hand-mouth contact and other motor patterns

Hand-mouth contacts (HMCs) and other spontaneous movements of five low-risk preterm infants were studied longitudinally after their birth until 60 weeks postmenstrual age. For all infants, HMCs that emerged in the preterm period could not be observed transiently after 45 weeks, however, they re-emerged after 50 weeks postmenstrual age. In actograms of the infants' behaviors, the frequency of other spontaneous movements, such as head rotation, showed the same re-emerging pattern. Movements such as cloni, which were also observed in the preterm period, decreased after the term period, with no subsequent increase. Only general movements were continuously present throughout the entire observation period; these changed from writhing to fidgety in nature around the third month. These findings clarify which spontaneous movements of preterm infants are important for later behavioral development.