It is normal for a 2-month-old child to have bent legs. High muscle tone within 3 months can make the legs unattractive or frog legs. This is a physiological curvature, which is a normal phenomenon. 6 months old or less presents frog legs, 2 weeks old or less appears O-shaped legs, 2-5 weeks old appears A-shaped, as long as the development is normal and the movement is normal, it should not be a big problem and does not need special treatment. The daily physiological requirement of vitamin D is at least 200 IU-400 IU for children half a month after birth, and vitamin D deficiency may lead to deformity of bones. Leg shape becomes unattractive, even O-leg aggravated, X-leg requires orthopedic treatment.