There are many causes of O-shaped legs in babies, such as physiological factors, walking earlier, rickets, etc. The causes of different correction methods are different, and it is recommended to consult a doctor for examination in time to clarify the causes and make improvements. 1. Physiological factors: many babies in 2-3 days after birth or 1-2 months the calf is bent, this is a normal phenomenon, is conducive to the delivery of the fetus. In this case, parents should pay attention to the observation, outpatient follow-up can be. 2. Early walking: babies who walk earlier are also prone to O-shaped legs, because their own bones and muscles are not fully developed, can not fully withstand the force of gravity, and most of the cases can be observed first. 3. Rickets: infant O-shaped legs caused by rickets need to supplement vitamin D to improve, such as vitamin D drops, vitamin D soft capsules, calcium, magnesium, zinc and copper vitamin D tablets, etc., you can also eat more vitamin D-rich foods, such as animal liver, eggs and so on. In general, most of the children with knee entropion within 1 ½ years of age can be observed and followed up in the outpatient clinic. For children over 1.5 years old, if the knee inversion is not corrected, they should go to the hospital to see a professional doctor in order to clarify the cause of the disease, and then consider whether to use a brace or surgical intervention.