Pregnant mothers are often either too fearful or too careless when it comes to medication during pregnancy. In fact, as long as the principles of medication are clearly understood, the drugs can be safe and secure for the pregnant mother herself and her fetus. Principle 1: Any medication should be taken under the guidance of a doctor and should not be purchased and taken on your own. Principle 2: If you take any medication, you should develop the habit of recording the medication used (name of the medication) so that you can clearly provide the name of the medication taken when needed to assess whether the medication is affecting the fetus and the extent of the effect. The habit of collecting and keeping the boxes and instructions of the medications taken during pregnancy is even more important. Principle 3: If you need to take medication for a long time because of special diseases such as abnormal thyroid function, epilepsy, systemic lupus erythematosus, etc., you should inform your doctor first and consult with him/her. Principle 4: Have regular prenatal checkups to understand the condition of the fetus. Principle 5: When taking medications, pay attention to the words “use with caution, contraindicated, or prohibited for pregnant women” on the package. Principle 6: Do not abuse drugs by listening to prescriptions or recipes. Principle 7: Never use drugs that can be used sparingly, and never use drugs that can be used or not. Drugs that have to be used need to be used under the guidance of a doctor. Principle 8: When two or more drugs have the same or similar efficacy, consider the drug that is less harmful to the fetus. Principle 9: Avoid combining drugs if you can use them alone, and avoid newer drugs if you can use drugs with more definite conclusions. Principle 10: The use of experimental drugs, including pregnancy tests, during pregnancy is prohibited. Principle 11: Medication must be administered with attention to the gestational week and with strict control of dosage and duration. Insist on reasonable use of medication and timely discontinuation of medication after the condition is controlled. Principle 12: If you have any problems with medication before or during pregnancy, you should consult with a professional doctor or pharmacist.