The normal range of vitamin D during pregnancy is between 75-375 nmol/L. Vitamin D is an important vitamin required for fetal growth and development and can play a role in promoting fetal bone development. If the concentration of vitamin D during pregnancy is between 51-75nmol/L, it is vitamin D deficiency, which may affect the growth and development of the fetus; or the fetus may have slow growth and development; or the fetus may have congenital calcium deficiency. If a woman has vitamin D deficiency during pregnancy, she should take vitamin D supplements, such as vitamin D drops, under the guidance of her doctor.