Spit up scare

This morning, the girls were snoozing in their baskets and I was answering emails on my computer when I looked over and saw that Maya's face was covered with spit up and she didn't seem to be breathing. I picked her up and held her head slightly down and rubbed her back and she eventually cleared out her nose and started breathing and crying again. When she started crying it was a very soft cry as she didn't have much air to cry with. This was obviously kind of terrifying - especially since I wonder what would have happened if I hadn't noticed that she was choking. I called the pediatrician and she said that she's never heard of an infant choking to death on spit up, but we could try to put her to sleep on her side so it's easier her to clear her airway if she does spit up in her sleep again.