I hate it when my son sleeps on his sides.. I'm so afraid of sids. he keeps laying on his sides. he's 2 weeks old.
I would roll up some receiving blankets and put them on both sides of baby.... of course shoulder length and lower so they don't turn their head into the blanket. but it worked for my baby for a little while until she was bigger and stronger with her head and neck.
I got him in a pack and play now.