A 5-month-old baby may barely be able to sit, but it is not recommended that a 5-month-old baby be allowed to sit alone, as there is a risk of injury to the baby’s spine. Generally speaking, infants around 6 months old have already learned to sit alone. 5-month-old infants may also try to sit up, but they may not be able to sit steadily because their spine is not fully developed and their muscles are not strong enough. Moreover, it is not recommended for 5-month-old infants to practice sitting alone, otherwise it may damage the spine of the infant and affect normal development. 5-month-old infants can sit against their parents, and do not sit for too long at a time. As the infant develops, the spine gradually matures and the strength of the back muscles gradually increases, so the infant can sit more steadily and for a longer period of time.