The baby’s legs are bent may be caused by physiological factors, heredity, rickets and other factors. 1. Physiological factors: infants and young children are young, the muscle tone of the inner thigh may be higher than the outer side, there will be a bent leg, usually no other clinical manifestations, with physical development will return to normal. 2. Heredity: one of the parents has a bent leg condition, which may be passed on to the child, resulting in the baby’s bent leg, but there are no other abnormalities. 3. Rickets: the lack of vitamin D in the baby’s body will cause abnormal absorption of calcium, which can cause rickets, which will lead to the baby’s legs are bent, and may also be accompanied by more than crying in bed, sleep is not stable and other abnormal manifestations. The baby’s legs are bent, and there are other abnormal phenomena, it is recommended to consult a doctor for examination and treatment, to avoid delaying the condition.