The amount of vitamin B12 to be taken varies with each pregnant woman’s health condition and needs to be prescribed by the doctor. Vitamin B12 is a water-soluble vitamin that can be used to treat and prevent vitamin B12 deficiency. It is mentioned in the instruction manual that the dosage for oral administration of this drug is 25-100 μg a day or 50-200 μg every other day in divided doses. Since pregnant women are a special group of people and every pregnant woman’s condition is different, how much they should take in a day should be in accordance with the doctor’s instructions. This drug may occasionally cause skin rash, itching, diarrhea and anaphylaxis and other adverse reactions. If pregnant women need to take this drug, it is recommended to use it under the guidance of a doctor and not to abuse it blindly.