Vitamins for pregnant women are usually better to start taking in the first 3 months of pregnancy, but the exact dosage should also be taken in the context of the pregnant woman’s own condition. Pregnant women usually need a multivitamin supplement, usually a multivitamin containing folic acid and vitamins. The medication is generally appropriate until about 12 weeks after conception, because the first three months is the critical period of fetal neurological development, supplementation of sufficient folic acid can reduce the risk of fetal neural tube development malformation, so supplementation of vitamins and folic acid at this time is very significant. Vitamins are essential nutrients for the human body, and if there are no special circumstances, the medication can be gradually discontinued after about 3 months. If there are serious vitamin deficiencies, the duration of the medication can be extended. Pregnant women may experience gastrointestinal disorders and other adverse reactions during administration of the drug. The drug should be contraindicated in pregnant women if they have hypervitaminosis A, hypervitaminosis D, hypercalcemia, hypercalciuria, renal insufficiency and so on. In addition, the drug should be used under the guidance of a doctor, avoid unauthorized use of the drug to avoid adverse effects. If pregnant women experience any of the above symptoms during the use of the drug, the drug should be discontinued, and it is recommended to consult a doctor in a timely manner, complete the relevant examinations under the guidance of the doctor, clarify the cause of the disease, and provide symptomatic treatment.