Yup - I use a little warmer that you heat up in the microwave (then place it under a blanket). I always wrap it TIGHTLY and keep a close eye on the babies to be sure they never wiggle under the blanket and lay on it directly. I'm also careful not to make it too hot - which means I am constantly warming it. I used to use heating pads, but they scare me. I'm just always so paranoid.

(Thats why I use a small stuffed animal to act as mama while they are young. If its too big, it will take them off the heat. Skylar still loves his "mama" stuffy he had when he was a wee one)