From the moment of birth, due to the influence of fetal position before birth, the difference of congenital constitution and the pressure of production process, the lower limbs of infants usually tend to be in the shape of "O" legs. This kind of "O" leg will bear the weight when learning to walk. Once it can't bear it, it will often get heavier and heavier. Under two years old, the limbs have the function of automatic correction, but they are easy to overcorrect and have "X" legs. When children are two to four years old, the joint load increases with the increase of weight and activity, and the incorrect sitting and squatting posture will be aggravated. Fortunately, after the age of four, I will correct myself automatically, and I will gradually get close to normal until I am six or seven years old. If rickets occurs in infancy, it will cause "X" or "O" legs. You need treatment at this time. Therefore, under normal circumstances, babies will have slight O-legs from birth to one year old, which is caused by genu varus. When they are one to two years old, they will gradually turn into eversion and slowly correct it. This is a normal phenomenon, but if the O-leg is too serious, such as varus over 15 degrees or over 2 years old, you must see a doctor.
It's normal to have legs that are not straight. When the baby is born, the legs are bent, which is the shape of the baby's legs in the mother's stomach. This situation will not get better until the baby learns to walk.