At this age, most babies are stable and can sit for longer periods of time. This is a major achievement, as it allows them to practice other skills like reaching, grabbing, and moving objects from hand to hand from an easier position. They have a new view of the world and new ways to interact with it. At the same time, babies’ growing curiosity and abilities lead them to try new things, so parents and caregivers should arrange the environment to minimize the possibility of falls, bumps, and bruises that can result from unexpected new movements. Even though they can sit on their own, babies at this age should never be left alone on a changing table, bed, couch, or other item to prevent dangerous falls.
Mercer, J. (1998). Infant development: A multidisciplinary introduction. Pacific Grove, CA: Brooks/ Cole.