Seven-month-old babies sometimes legs straighten hand shaking may be caused by the imperfect development of the nervous system, but also may be hypocalcemia, epilepsy, as well as other causes such as febrile convulsions. 1. imperfect development of the nervous system: generally seven months lesions of the nervous system development is not perfect, at this time the child may appear sometimes legs straight, hand shaking performance. 2. Hypocalcemia: Hypocalcemia may be caused by hypoparathyroidism, vitamin D deficiency and other reasons. The patient will appear hand and foot twitching, muscle spasm, sensory abnormalities and other manifestations, so the seven-month lesion of hypocalcemia will be manifested in the performance of sometimes straight legs, hand shaking. 3. Epilepsy: epilepsy may be caused by heredity, cortical development disorder, head trauma, brain tumor and so on. The patient will have generalized convulsions, paroxysmal spasms, continuous contraction of skeletal muscles all over the body, and corns. If a seven-month-old baby has epilepsy, he or she may sometimes have symptoms of leg extension and hand shaking. 4. other: seven months of the baby sometimes legs straight hand shaking may also be high fever convulsions, encephalitis and other causes. Seven months of the baby sometimes legs straight hand shaking need to take the baby to the hospital in time to check, if the neurological development is not perfect due to, without treatment. If the disease is caused by the need to address the cause of treatment.