Which of the following is NOT a known risk factor of SIDS?

Putting a baby to sleep on his or her back is actually a widely accepted practice for reducing the risk of Sudden Infant Death Syndrome (SIDS). This 'back-to-sleep' position has been endorsed by health organizations as part of a safe sleep campaign. Research has shown that infants who are placed on their backs to sleep are significantly less likely to experience SIDS compared to those who are placed on their stomachs or sides.

In contrast, the other options listed are associated with an increased risk of SIDS. For instance, sleeping on the side can lead to an increased risk of the baby rolling onto their stomach, which is an unsafe position. Soft bedding can create a risk of suffocation or rebreathing exhaled air, and maternal smoking is a well-documented risk factor that affects an infant's respiratory system. Therefore, putting a baby to sleep on their back is a key protective measure against SIDS.