For many years, it had been recommended that infants, particularly in the age range from birth to four months, be placed on their stomachs for sleep. This was thought to be the best way to avoid aspiration (sucking food into the trachea or windpipe) in case of vomiting or spitting up.
Recent information, however, indicates that the back is a safer position, particularly as it relates to Sudden Infant Death Syndrome (SIDS). Therefore, the American Academy of Pediatrics recommends that healthy infants be placed on their backs for sleep.
Although sleep position is probably not the only reason for SIDS, it seemed so strongly related that the Academy felt obligated to make this recommendation. Please note that there are some exceptions to this new recommendation, which your pediatrician can discuss with you.
This recommendation applies to infants throughout the first year of life. However, the recommendation is particularly important the first six months of life, when the incidence of SIDS is highest.
It is also important to avoid placing your baby down for sleep on soft, porous surfaces such as pillows or quilts. Their airway may become blocked if their face becomes burrowed in such surfaces. A firm crib mattress covered by a sheet is the safest bedding.
There is no reason to restrict your baby sleeping in their crib. If, for any reason, you want them closer to you while they sleep, use a bassinet or pack and play as a temporary crib and move it around the house with you.