Which practice is considered unsafe regarding infant sleep?

Sleep surface sharing is considered unsafe regarding infant sleep primarily due to the increased risk of suffocation and accidental injury. When an infant shares a sleep surface, such as a bed with an adult or on a couch, the likelihood of the infant being trapped or rolling off increases, which can lead to dangerous situations. Additionally, factors like bedding materials or an adult's movements during sleep can pose risks to the infant’s safety.

In contrast, using a crib provides a designated, safe sleep space designed specifically for infants, which helps to minimize hazards. Placing infants on their back is a recognized practice for reducing the risk of Sudden Infant Death Syndrome (SIDS), and is recommended by health professionals. Co-sleeping, while often debated, may also involve specific conditions that could be safe if followed properly, though it generally comes with a higher risk compared to the recommended sleeping arrangements.