Start in a dream is quite natural to a children's organism. The child could overtire from games and communication before going to bed therefore strongly you should not worry about it. But it concerns only isolated cases as continuous and long start is a serious reason for the address to the doctor.
Any unclear changes in work of an organism of the child raise the mass of questions and fear at their mothers. It is possible to refer to such phenomena also start in a dream. As a rule, having noticed it at the child, many young mothers at once see a doctor. But in most cases there are no reasons for medical intervention just as starts are quite natural during sleep both to the adult, and to a young organism.
Often involuntary movements are observed during sleep at newborn babies. The child adapts to independent life. Thus the systems of its organism adapt to the world around. He can shudder because of imperfection of brake mechanisms of nervous system upon transition from one stage of a dream to another or because of overfatigue.
At children is more senior than month these involuntary movements can speak about problems with a tummy. Digestive system of an organism also adapts therefore there can be gripes or other unpleasant feelings. Children of a year are also more senior can shudder from overexcitation or fatigue. It can be promoted by active games, excessive training or communication. Often there is it that the child overexcited from emotions cannot fall asleep and when nevertheless fills up, his organism begins to react to fatigue starts. Therefore it is before going to bed better to devote time to reading or some "silent" games. If starts in a dream repeat regularly and often, then it is a good reason for the request for medical care as such symptoms can speak about problems with nervous system or with a metabolism (can lead to appearance of spasms). A reason for a campaign to the doctor is also the excessive rhythm of starts. Only the expert will be able to give the qualified advice therefore by national methods you should not be engaged in self-treatment.