Baby Milestones: Gross Motor Development Throughout the first three years, babies progress from more or less stationary beings with little body control to explorers who can roll, sit, crawl, stand, and walk. They learn how to keep their balance and to throw or catch objects. Once this happens, the main milestones of gross motor development have been achieved. Newborns have motor reflexes to interact with their physical environment. Voluntary movements are also possible but not yet well adjusted. During the first weeks of life, infants learn to keep their heads in a stable position without support, before they learn to lift their upper bodies while lying on their tummies. A few months later, another milestone is reached: they can roll from tummy to back and vice versa. Most infants start to move forward and backwards on the floor by four to six months. When lying on their tummy and lifting …