19wks pregnant, while sleeping I turn from side to side. I repeatedly change my positions. But I don't sleep on my back. Am I harming my baby by turning?

No. Being pregnant can be scary & we often fear that simple things we do can be harmful. Your baby is well protected in your uterus by the sac of fluid (amniotic sac) that it is in. Even when you lie perfectly still- the baby will be moving inside of you on its own. Breathe easy knowing that your tossing & turning doesn't hurt. It may help you to get a body pillow so you can get a good night sleep.