Hello, I m 42-years-old, 5 3 , 160lbs, 23 weeks pregnant. This morning at 4am I woke up extremely cold, shivering, and chattering teeth. The symptoms subsided in about 15 to 20 minutes after I covered myself with a warm blanket. This was the second episode I ve experienced during pregnancy. Is it harmful to the baby? Should I be concerned? What can I do to prevent this from happening again? Thank you.