Don't know about in utero, but when my best gf's DS was born he had the shakes for almost a week, particularly if he was unwrapped. The paed said it was an underdeveloped nervous system (and the little man was already a week overdue, but no wonder he didn't want to come out - he wasn't ready!). So perhaps it could have happened in utero too. My gf's placenta was at the front so she didn't feel a lot of movement.