The ontogeny of limbs movements towards midline in healthy infants born at term

Background: Movements towards midline are part of the age-adequate motor repertoire of infants. They develop contemporaneously to general movements, changing from occasional simple contact to proper midline motor patterns.
Aim: The aim of this study is to describe the ontogeny of movements towards midline in full term healthy infants.
Study design:Parents were asked to record their infant every second week, from term age to 22 weeks post-term.
Subjects:25 healthy full-term infants.
Result: Three main epochs of development were detected: in the first one, between birth and 4 weeks post-term, movements towards midline were occasional, apparently due to the dominant flexed posture of elbow and knees and the adducted posture of shoulders and hips. In the second epoch, from 4 to 8 weeks, the limbs movements towards midline markedly decreased. In the third one, after 8 weeks, movements towards midline increased again in frequency, first appearing in lower limbs then in upper limbs, first solely as contact and thereafter as manipulation. A temporal overlapping with the occurrence of intermittent or continual fidgety movements was detected.
Conclusions: Movements towards midline progressively change, through a defined timeline, in full term healthy infants. The increased knowledge about the normal age-adequate motor repertoire can help physicians in clinical assessment of high risk infants.