Rational use of drugs during pregnancy Before the 1950s, although it was known that some drugs could cause miscarriage or stillbirth during pregnancy, it was not recognized that drugs could cause fetal malformations. In the 1960s, a new drug, “Reactive Stop”, was developed to treat pregnancy reactions and was used in 17 countries around the world. However, 15,000 newborns with Phecomelia or limb deformities were soon born. It was also reported that some of the daughters born to pregnant women who were taking hexestrol at the time developed vaginal adenopathy in adolescence, and even transformed into clear cell carcinoma of the vagina. This is a cause for concern. As a result, there is a misconception among pregnant women and some medical professionals that the use of drugs during pregnancy can lead to fetal malformations. For this reason some doctors are overly cautious to use drugs for pregnant women. Sometimes, due to the lack of understanding of the relationship between drugs and birth defects, doctors often inappropriately advise pregnant women to terminate their pregnancies. Ma| of the Infertility Treatment Center of Qilu Hospital of Shandong University Many women do not have a planned pregnancy but an unplanned one, so they may have taken some medication before they learned they were pregnant and are worried about how the medication will affect the fetus. Some women are already suffering from some chronic diseases that require long-term medication when they start their pregnancy. However, they are afraid that the medication will affect the fetus and expect to receive explanations and guidance from their doctor. Clinical studies have shown that only a small percentage of malformations, about 1% to 2% of the total, are thought to be related to the use of drugs during pregnancy. I. Guidance system for the use of drugs during pregnancy and lactation A guidance system for the use of drugs during pregnancy and lactation was first established in Sweden in 1978. The drugs were classified into seven classes: A, B1, B2, B3, C, D, E. In 1979, the U.S. FDA followed suit and established a classification system for the use of drugs during pregnancy with five classes: A, B, C, D, X. Australia and Germany also established their own classification systems. Australia and Germany have also established their own systems. At present, there is no official document on the use of drugs during pregnancy in China. Most of China’s pharmacy system refers to the documents published by the US FDA. The FDA classifies drugs into five risk classes according to their harmfulness to the fetus: Class A In studies with control groups, no signs of harm to the fetus were found in women in the first trimester (and no evidence of harm in the following 6 months). Grade B No adverse effects on the fetus were seen in animal reproduction studies (no controlled studies in pregnant women), or no side effects were found in animal reproduction studies. Grade C: The drug has been shown to be harmful to the fetus (teratogenic or embryonic death) in animal studies, or no control group of pregnant women and animals has been studied. This class of drugs should be used only after weighing the benefits to the pregnant woman against the risks to the fetus. Class D There is a clear evidence that the drug is harmful to the human fetus. However, despite this, there is an absolute benefit to pregnant women when the drug is administered (e.g., the drug is used to save the life of a pregnant woman or to treat a disease that is not effective with other safer drugs). Class X Drugs are contraindicated in women who are or may become pregnant because animal and human studies or human experience with the drug indicate that the drug is harmful to the fetus and that there is no benefit to pregnant women from the use of such drugs. II. Antibiotics Chloramphenicol, aminoglycosides and tetracyclines belong to Class D. Sulfonamides mostly belong to class C. Most of the drugs of quinolones belong to class C. Including norfloxacin, ofloxacin, levofloxacin ciprofloxacin, etc. Most of the penicillins belong to category B. It is also safe to apply during lactation. Most of the macrolide antibiotics are included in category B. For example, erythromycin, roxithromycin, azithromycin, etc. are safer to use during pregnancy. Spiramycin and clarithromycin are in FDA category C again. 2. Anti-tuberculosis drugs Isoniazid, Rifampicin belong to category C. 3. Anti-viral drugs Most of them belong to category B. Ganciclovir belongs to category D. 4. Drugs for vaginitis Clindamycin (clindamycin), an effective drug for treating bacterial vaginosis, is classified as category B by the FDA and is included in category A in Sweden. However, do not apply during breastfeeding. Metronidazole is in category B. Clotrimazole is in category B, such as Kenitin, and Dacrynic acid is in category C. Fluconazole belongs to category C. 5. Anti-arrhythmic drugs Most of the Lore group belong to class C, a few are class B, but in the middle and late stages of pregnancy all belong to D. 6. Anti-hypertensive drugs Most of the epinephrine, norepinephrine, isoprenaline, phenylephrine, meprobamate, dopamine, etc. belong to class B. 7. Most of the drugs of digestive system belong to class B. 10. diuretics Thiazides belong to class C, such as ketorolac, tab diuretics belong to class C, such as furosemide, tachyphylaxis, potassium-protecting diuretics spironolactone, aminoglutethimide belong to class C. Mannitol and sorbitol belong to class B. 11. Most hemostatic drugs belong to class A or B. Most hemopoietic drugs belong to class A or B. Most of the hemopoietic drugs belong to class A or B. Most anticoagulants belong to class C or D: low molecular heparin belongs to class B, heparin belongs to class C, warfarin belongs to class D, aspirin belongs to class C. 12. The effect of drugs on embryo in different periods 1. Pre-embryonic period From the beginning of conception to the 14th day after conception. Any side effects caused by the drug during this period will produce an “all or nothing phenomenon”, i.e. any stimulation may result in the death of the blastocyst and abortion or absorption, or the embryo may be unaffected by the proliferation of totipotent cells. 2. Embryonic period From the 3rd week after conception to the 8th week after conception, this period is also the most important period for organ formation. Theoretically, this is the period of highest sensitivity of the embryo, rapid differentiation of tissues and the greatest risk of congenital malformations, leading to irreparable damage of any kind that occurs during this period. 3. Fetal period From the 9th week after conception to the full term of gestation. During this period, drugs can affect the growth and development of the fetus via the placenta without causing fetal gross structure. In general, the dose of drugs affecting the fetus is correlated with the consequences, the total amount being higher and the consequences more severe. Of course, this is not entirely true. Streptomycin, for example, can cause damage to the auditory nerve even in small amounts. The sensitivity of the fetus to the drug is also an important factor, and the consequences of the same drug, at the same dose, vary. Therefore, the indications for the use of drugs during pregnancy should be strictly controlled. Pay attention to the sensitivity period of the fetus to drugs. We need to understand the effects of the drugs used on the fetus and the possible effects on the fetus and weigh the pros and cons to guide the clinical use of the drugs.