My baby is 4months old. He still is not rolling over to his tummy. When should this be a cause of worry. Please advise. #AskTheExpert

A. Your baby may be able to kick over from their tummy to their back as early as 3 to 4 months old. It usually takes them until about 5 or 6 months old to flip from back to tummy, though, because they need stronger neck and arm muscles for that maneuver.