Explanation
Preterm infants have low muscle tone, and large sudden and jerky arcs of spontaneous movement; this makes it difficult for them to control their movements against gravity. Their posture is hence completely dependent on the support they are lying on. This is in contrast to the foetus, supported in a flexed posture and able to learn to move within the amnioitic fluid. Consequently they are vulnerable to soft tissue imbalance and skeletal deformity, e.g. abducted hips, plagiocephally