Final answer:
Co-sleeping was a common practice in the USA until shortly after the 20th century, affected by social and economic changes. Infant sleep safety concerns, particularly related to SIDS, led to recommendations against co-sleeping to reduce risks.
Step-by-step explanation:
The practice of co-sleeping was usual in the USA until about shortly after the beginning of the 20th century. This communal sleeping arrangement was not just about warmth and safety, but also due to the scarce living conditions, where families with multiple children and even boarders would often share the same sleeping quarters due to lack of space and resources. Over time, social and economic changes, such as improved housing conditions and the advent of better birth control methods leading to smaller family sizes, played a role in the reduction of co-sleeping.
In relation to infant sleep safety, it was observed that certain sleeping practices, such as placing infants on their backs to sleep and avoiding soft bedding like pillows and blankets, could help reduce the risk of Sudden Infant Death Syndrome (SIDS), leading to a shift in parenting practices. Nowadays, numerous recommendations are given to parents to protect their infants from SIDS, including the avoidance of co-sleeping as a way to reduce the risk.