A majority of babies seem from the beginning to be a little more comfortable going to sleep on their stomach. This is particularly true of the baby who develop colic; the pressure on the abdomen seems to partly relieve the gas pains.
Others either don't care at first or prefer sleeping on their back. There are two disadvantages to a baby sleeping on his back. If he vomits, he's more likely to choke on the vomits. Also he tends to keep his head turned toward the same side-usually toward the center of the room. This may flatten that side of his head. It won't hurt his brain and the head will gradually straighten out, but it may take a couple of years.
