Bent legs in infants do not necessarily need to be corrected, it depends on the baby’s age and condition. 1. The fetus is flexed in the uterus, and the tension of the flexor muscles is a little stronger than that of the extensor muscles after birth, so the legs are bent. Coupled with the fact that human growth and development follows a top-down pattern, the muscles and bones of the lower limbs develop later. With age, the bones and muscles develop gradually, and the tension of flexor and extensor muscles is gradually balanced, so the infant’s leg curvature can then be improved. 2. Generally, babies at the age of 2 will have mild O-shaped legs (inward turning of the knee), and between the ages of about 2 and 4, the legs of babies will gradually straighten into mild X-shaped legs (outward turning of the knee), and after the age of 7, the legs of babies will slowly straighten out. 3. If the baby’s legs are bent severely, affecting the activities, it may be O-shaped legs, X-shaped legs and other bone deformities caused by rickets, or congenital developmental deformities of the leg bones, which need to go to the hospital in time to improve the relevant examination and treatment for the cause. When parents find that their baby’s legs are bent, it is recommended that they take their baby to the hospital for a clear diagnosis.