During this time, a baby becomes increasingly mobile and able to get into a potentially suffocating position. Some babies have an abnormality in their arcuate nucleus, a region in the brain that controls breathing, heart rate, sleep, and waking. One possible cause for the defect is a mother's smoking, which reduces the flow of oxygen to a fetus. An infant sleeping facedown may rebreathe her own exhaled carbon dioxide and asphyxiate. Soft bedding has been implicated not only in the deaths of stomach sleepers, but also in those of back sleepers who pull covers over their heads.
Excessive heat can lead to deeper sleep, preventing a baby's arousal.
Put your baby to sleep on his back. An infant who usually sleeps on his back is at an even greater risk of SIDS when placed on his stomach. Place your baby on a firm mattress. Avoid waterbeds, pillows, sheepskins, or other plush surfaces. Keep it simple.