My 3 month old dd has always favoured the left side of her head. So when I put her down to sleep, she sleeps with her head to the left side (the side of her face flat to the mattress), if I put her in her swing she turns her head to the left. She can hold her head up straight but when her neck gets tired her head falls to the left. She can definitely move her neck around to both sides as she does this when following me around the room or when she tries to look at the TV.
Is this a problem and something I need to contact a Dr about?