The FDA classification of medications used in pregnancy and its criteria according to the U.S. Food and Drug Administration (FDA) standards, the safety of drugs in pregnancy is divided into five categories: A, B, C, D, X. Some drugs have two different levels of risk, one is the level of the commonly used dose, and the other is the level of the exceedingly used dose. The criteria for the five classifications are described as follows:FDA-A: No risk to the fetus has been shown in early pregnant women with controls (and no evidence of risk in intermediate and late pregnancies), and there may be minimal harm to the fetus.FDA-B: Risk to the fetus has not been shown in animal reproduction tests but there are no pregnant women with controls, or there have been side effects shown in animal reproduction tests (less severe than infertility) but No side effects were confirmed in control groups of women in early pregnancy (and no evidence of risk in middle or late pregnancy) FDA-C: Side effects on the fetus (teratogenic or embryonic lethal or other) were confirmed in animal studies, but there were no control groups of women or there was no available information in studies in women and animals. Drugs are given only when the benefits to the fetus are weighed against the harms.FDA-D: Risk to the human fetus has been positively documented, but despite the harm, the benefit to the pregnant woman needs to be positively documented for application (e.g., in cases of end-of-life or serious illness where a safer drug cannot be applied or where the drug is ineffective).FDA-X: Abnormalities have been demonstrated to cause abnormalities to the fetus in studies in animals or in humans, or are known to pose a risk to the fetus based on experience in humans. Harmful to humans or both, and the drug is used in pregnant women where the risk clearly outweighs any benefit. The drug is contraindicated in women who are or will be pregnant. A brief introduction to each classification of drugs 1, FDA – Class A drugs: very few, vitamins belong to this type of drug, such as various vitamins B, C, etc., but in the normal range of doses of vitamin A is a class A drug, while large doses of vitamin A, the daily dose of 20,000 IU, can cause teratogenicity, and become a class X drug. 2, FDA – Class B drugs: also not a lot of commonly used antibiotics belong to this type of drug. Such as all the penicillin family and the vast majority of cephalosporins are class B drugs, commonly used ampicillin, cephradine, cefotrizine (cefatrizine, trade name of the bacterium or called Rothfen) and serious infections with rescue cefotaxime (cefazidime, trade name of fudaxin) and so on are class B drugs. In addition, Zeomicin, Clindamycin, Erythromycin, and Furotoxin are also class B drugs. In addition, metronidazole is known to be a drug for trichomoniasis, but it is also an excellent drug for anaerobic infectious diseases. Although in animal experiments, it can be teratogenic to rodents, but for humans, a large number of clinical data accumulated over a long period of time has confirmed that the application of early pregnancy did not increase the rate of fetal teratogenicity, so in the FDA classification of drugs in pregnancy metronidazole is placed in Class B. Among antituberculosis drugs, ethambutol is a Class B drug. Among the commonly used antipyretic and analgesic drugs, indomethacin (消炎痛), diclofenac (fu-talin), and ibuprofen (fen-phen) are all class B drugs. However, it should be noted that after 32 weeks of pregnancy, taking indomethacin may cause the fetus to develop arterial stenosis or atresia, resulting in fetal death. indomethacin should not be taken after 32 weeks. Among the cardiovascular system drugs digitalis, digoxin and trichoside C (sildenafil) are class B drugs. Prednisone, an adrenocorticotropic hormone that can damage the fetus, also belongs to Class B. 3, FDA-C drugs: more. This class of drugs or the introduction of time is not long enough or less in the application of pregnant women, mainly in early pregnancy on the fetus will cause damage has not been reported, so it is difficult to have a more definitive conclusion. To antibiotic quinolones, for example, this class of drugs in animal experiments found that ofloxacin damage to cartilage, in humans there have been reports of more than 600 cases of early pregnancy to take the drug, after delivery of the child’s growth period of 6 cases of pain in the legs and so on, but the symptoms disappeared soon after, none of the sequelae, so that the data of the argument, this drug is still safe. However, the clinic is still waiting for more reports to confirm its harmlessness. There are also prospective studies on the safety of such drugs, such as Adam observed 0.1 a lla of pediatric 50 cases, po tartrazine acid 10-815d, dose; 50mg/(kg-d), clinical observation and X-ray pick up no abnormality, height has no effect. Another study found that the concentration of drugs in fetal cartilage after pregnant women poCIX is higher than the concentration of fetal plasma drugs, although fetal cartilage gross observation and light microscopy pick up are not abnormal, but the ultrastructure of the same pathomorphological changes as animal cartilage, namely, the degeneration of chondrocytes and the loss of matrix. Caution should be exercised in the use of class C drugs, if there is an alternative drug available then the alternative drug is chosen, otherwise after weighing the pros and cons, the rationale for the choice of the drug is explained to the patient or the patient’s family. Take tuberculosis as an example: as commonly used anti-tuberculosis drugs only ethambutol a class B drug, and anti-tuberculosis treatment is often a number of drugs combined treatment, so we need to consider the application of p-amino-salicylic acid sodium (sodium-aminosalicylate), isoniazid (isoniazid), and other drugs of the class C. If the patient is in the early stages of pregnancy and the combination of pulmonary tuberculosis, it should be explained to the patient. The situation. Most of the antiviral drugs belong to category C, such as acyclovir (acyclovir) and zidovudine (zidovudine) for AIDS. Some of the antiepileptic drugs and tranquilizers such as ethosuximide (ethosuxan), felbamate (felbamate), barbiturates, and pentobarbital. Among the autonomic nervous system drugs, cholinergics and anticholinergics belong to class C. As for the adrenergics, some of them belong to class C, such as epinephrine, ephedrine, dopamine and so on. Antihypertensive drugs such as methyldopa, prazosin and all commonly used vasodilators, such as phenamphetamine, amlazoline, pentylenetetrazol, belong to class C. Diuretics such as furosemide (tachycardia) and mannitol are all class C drugs. In the adrenocorticotropic hormone drugs, betamethasone and dexamethasone are class C drugs.4, FDA-D drugs: due to the experimental and clinical evidence, the classification of drugs belonging to the D in pregnancy, especially in the early stages of pregnancy as far as possible not to use. In the antibiotic tetracycline family is a typical, pregnancy with tetracycline or oxytetracycline, destruction of fetal tooth enamel, to the adult teeth yellow, which is the consequence of the use of tetracycline drugs. Aminoglycosides, such as streptomycin, should not be used in pregnancy as much as possible, as they may damage the eighth pair of cranial nerves and cause hearing loss. As for antineoplastic drugs are almost all class D drugs, methotrexate (MTX) for example, in the late 1940s, it was recognized that in leukemia combined with pregnancy application of MTX can occur chorionic villus necrosis and lead to miscarriage, so in the early 1950s Hertz et al. developed the idea of using MTX to treat choriocarcinoma and achieved success, and to this day, MTX has been Nowadays, MTX has been widely used in the treatment of trophoblast-related diseases, such as ectopic pregnancy, placental implantation, etc.; other antitumor drugs, such as cisplatin, 5-fluorouracil, etc., have also joined the ranks. Therefore, antitumor drugs are prohibited in pregnancy. In the central nervous system drugs in the analgesic, small doses of B drugs, large doses of D drugs, especially long-term application of harmful to the fetus, the main manifestation of fetal growth and development as well as addiction to drugs after delivery, restlessness, crying and so on. Many of the antiepileptic drugs are class D drugs, such as paracetamol (primidone), trimethadione (trimethadione), etc. have teratogenic effects, it is important to note that after pregnancy in epileptic patients, the malformation rate of the fetus is higher than that of the general population, and the use of antiepileptic drugs can increase the rate of malformations, especially when several types of antiepileptic drugs are used simultaneously in difficult to control seizures, then it is even more likely to increase the rate of fetal malformations. This is something that needs to be made clear to the patient and family when diagnosing and treating epilepsy in combination with pregnancy. In the sedative and hypnotic drugs diazepam (diazepam, Valium), chlordiazepoxide (chlordiazepoxide, Librium), meprobamate (meprobamate, sleep and pass) and norethindrone (oxazepam) are class D drugs, such as pregnant women in the early stages of pregnancy with early pregnancy reaction and insomnia and other symptoms, can not be given to the class of drugs. In diuretics, hydrochlorothiazide (hydrochlorothiazide, dihydroclonidine), etanercept (ethacrynic acid, diuretic acid), benzylserazine (benzthiazide) are class D drugs and should not be used in pregnancy. As for the antipyretic and analgesic drugs in aspirin (aspirin), double salicylic acid, sodium salicylate (sodiumsalicylate) in small doses for the use of class C drugs, but long-term large doses of drugs, and sometimes even addictive, it is unfavorable to the fetus and become class D drugs. In fact, there are thousands of medications available for people to use, and there are B, C, and D drugs in all kinds of medications, so people can choose B or C drugs instead of D drugs. The FDA classification of drugs used in pregnancy and its standards according to the U.S. Food and Drug Administration (FDA) standards, the safety of drugs in pregnancy is divided into five categories: A, B, C, D, X. Some drugs have two different levels of risk, one is the level of the commonly used dose, and the other is the level of the exceedingly used dose. The five classifications are described as follows: FDA-A: No risk to the fetus has been demonstrated in early pregnant women with controls (and there is no evidence of risk in intermediate and late pregnancies), and there may be minimal harm to the fetus. Kaiyu Zhou, Department of Pediatric Cardiovascular Medicine, West China Second Hospital of Sichuan University FDA-B: No risk to the fetus was demonstrated in animal reproduction tests, but there were no control groups of pregnant women, or side effects were demonstrated in animal reproduction tests (less severe than infertility) but were not confirmed in control groups of women in early pregnancy (and there was no evidence of risk in intermediate or late pregnancy).FDA-C: A side effect to the fetus was demonstrated in animal studies (and there was no evidence of risk in intermediate and late pregnancy).FDA-C: A side effect to the fetus was demonstrated in animal studies (and there was no evidence of risk in intermediate and late pregnancy). Fetal side effects (teratogenicity or embryonic lethality or other) have been demonstrated in animal studies, but there are no controls in women or no available information in women and animal studies. The drug is given only when the benefits to the fetus are weighed against the harms.FDA-D: There is positive evidence of risk to the human fetus, but despite the harms, the benefits to the pregnant woman need to be certain in order for the drug to be used (e.g., in cases of end-of-life or serious illness where a safer drug cannot be applied or the drug is ineffective).FDA-X: It has been shown to cause fetal abnormality in animal or human studies, or is known to be dangerous to the fetus on the basis of human experience. Harmful to humans or both, and the drug is used in pregnant women where the risk clearly outweighs any benefit. The drug is contraindicated in women who are or will be pregnant. A brief introduction to each classification of drugs 1, FDA – Class A drugs: very few, vitamins belong to this type of drug, such as various vitamins B, C, etc., but in the normal range of doses of vitamin A is a class A drug, while large doses of vitamin A, the daily dose of 20,000 IU, can cause teratogenicity, and become a class X drug. 2, FDA – Class B drugs: also not a lot of commonly used antibiotics belong to this type of drug. Such as all the penicillin family and the vast majority of cephalosporins are class B drugs, commonly used ampicillin, cephradine, cefotrizine (cefatrizine, trade name of the bacterium or called Rothfen) and serious infections with rescue cefotaxime (cefazidime, trade name of fudaxin) and so on are class B drugs. In addition, Zeomicin, Clindamycin, Erythromycin, and Furotoxin are also class B drugs. In addition, metronidazole is known to be a drug for trichomoniasis, but it is also an excellent drug for anaerobic infectious diseases. Although in animal experiments, it can be teratogenic to rodents, but for humans, a large number of clinical data accumulated over a long period of time has confirmed that the application of early pregnancy did not increase the rate of fetal teratogenicity, so in the FDA classification of drugs in pregnancy metronidazole is placed in Class B. Among antituberculosis drugs, ethambutol is a Class B drug. Among the commonly used antipyretic and analgesic drugs, indomethacin (消炎痛), diclofenac (fu-talin), and ibuprofen (fen-phen) are all class B drugs. However, it should be noted that after 32 weeks of pregnancy, taking indomethacin may cause the fetus to develop arterial stenosis or atresia, resulting in fetal death. indomethacin should not be taken after 32 weeks. Among the cardiovascular system drugs digitalis, digoxin and trichoside C (sildenafil) are class B drugs. Prednisone, an adrenocorticotropic hormone that can damage the fetus, also belongs to Class B. 3, FDA-C drugs: more. This class of drugs or the introduction of time is not long enough or less in the application of pregnant women, mainly in early pregnancy on the fetus will cause damage has not been reported, so it is difficult to have a more definitive conclusion. To antibiotic quinolones, for example, this class of drugs in animal experiments found that ofloxacin damage to cartilage, in humans there have been reports of more than 600 cases of early pregnancy to take the drug, after delivery of the child’s growth period of 6 cases of pain in the legs and so on, but the symptoms disappeared soon after, none of the sequelae, so that the data of the argument, this drug is still safe. However, the clinic is still waiting for more reports to confirm its harmlessness. There are also prospective studies on the safety of such drugs, such as Adam observed 0.1 a lla of pediatric 50 cases, po tartrazine acid 10-815d, dose; 50mg/(kg-d), clinical observation and X-ray pick up no abnormality, height has no effect. Another study found that the concentration of drugs in fetal cartilage after pregnant women poCIX is higher than the concentration of fetal plasma drugs, although fetal cartilage gross observation and light microscopy pick up are not abnormal, but the ultrastructure of the same pathomorphological changes as animal cartilage, namely, the degeneration of chondrocytes and the loss of matrix. Caution should be exercised in the use of class C drugs, if there is an alternative drug available then the alternative drug is chosen, otherwise after weighing the pros and cons, the rationale for the choice of the drug is explained to the patient or the patient’s family. Take tuberculosis as an example: as commonly used anti-tuberculosis drugs only ethambutol a class B drug, and anti-tuberculosis treatment is often a number of drugs combined treatment, so we need to consider the application of p-amino-salicylic acid sodium (sodium-aminosalicylate), isoniazid (isoniazid), and other drugs of the class C. If the patient is in the early stages of pregnancy and the combination of pulmonary tuberculosis, it should be explained to the patient. The situation. Most of the antiviral drugs belong to category C, such as acyclovir (acyclovir) and zidovudine (zidovudine) for AIDS. Some of the antiepileptic drugs and tranquilizers such as ethosuximide (ethosuxan), felbamate (felbamate), barbiturates, and pentobarbital. Among the autonomic nervous system drugs, cholinergics and anticholinergics belong to class C. As for the adrenergics, some of them belong to class C, such as epinephrine, ephedrine, dopamine and so on. Antihypertensive drugs such as methyldopa, prazosin and all commonly used vasodilators, such as phenamphetamine, amlazoline, pentylenetetrazol, belong to class C. Diuretics such as furosemide (tachycardia) and mannitol are all class C drugs. In the adrenocorticotropic hormone drugs, betamethasone and dexamethasone are class C drugs.4, FDA-D drugs: due to the experimental and clinical evidence, the classification of drugs belonging to the D in pregnancy, especially in the early stages of pregnancy as far as possible not to use. In the antibiotic tetracycline family is a typical, pregnancy with tetracycline or oxytetracycline, destruction of fetal tooth enamel, to the adult teeth yellow, which is the consequence of the use of tetracycline drugs. Aminoglycosides, such as streptomycin, should not be used in pregnancy as much as possible, as they may damage the eighth pair of cranial nerves and cause hearing loss. As for antineoplastic drugs are almost all class D drugs, methotrexate (MTX) for example, in the late 1940s, it was recognized that in leukemia combined with pregnancy application of MTX can occur chorionic villus necrosis and lead to miscarriage, so in the early 1950s Hertz et al. developed the idea of using MTX to treat choriocarcinoma and achieved success, and to this day, MTX has been Nowadays, MTX has been widely used in the treatment of trophoblast-related diseases, such as ectopic pregnancy, placental implantation, etc.; other antitumor drugs, such as cisplatin, 5-fluorouracil, etc., have also joined the ranks. Therefore, antitumor drugs are prohibited in pregnancy. In the central nervous system drugs in the analgesic, small doses of B drugs, large doses of D drugs, especially long-term application of harmful to the fetus, the main manifestation of fetal growth and development as well as addiction to drugs after delivery, restlessness, crying and so on. Many of the antiepileptic drugs are class D drugs, such as paracetamol (primidone), trimethadione (trimethadione), etc. have teratogenic effects, it is important to note that after pregnancy in epileptic patients, the malformation rate of the fetus is higher than that of the general population, and the use of antiepileptic drugs can increase the rate of malformations, especially when several types of antiepileptic drugs are used simultaneously in difficult to control seizures, then it is even more likely to increase the rate of fetal malformations. This is something that needs to be made clear to the patient and family when diagnosing and treating epilepsy in combination with pregnancy. In the sedative and hypnotic drugs diazepam (diazepam, Valium), chlordiazepoxide (chlordiazepoxide, Librium), meprobamate (meprobamate, sleep and pass) and norethindrone (oxazepam) are class D drugs, such as pregnant women in the early stages of pregnancy with early pregnancy reaction and insomnia and other symptoms, can not be given to the class of drugs. In diuretics, hydrochlorothiazide (hydrochlorothiazide, dihydroclonidine), etanercept (ethacrynic acid, diuretic acid), benzylserazine (benzthiazide) are class D drugs and should not be used in pregnancy. As for the antipyretic and analgesic drugs in aspirin (aspirin), double salicylic acid, sodium salicylate (sodiumsalicylate) in small doses for the use of class C drugs, but long-term large doses of drugs, and sometimes even addictive, it is unfavorable to the fetus and become class D drugs. In fact, at present, people can apply for thousands of kinds of drugs, in all kinds of drugs have B, C, D class drugs, so people can choose B class drugs or C class drugs and not use D class drugs. 5, FDA-X class drugs: in the common use of this kind of drug is not much, but because of the high rate of teratogenicity, or on the fetus is very harmful, pre-pregnancy and pregnancy is prohibited. The most famous is phthalidomide piperidone (thalidomide, reaction stop), the late 1950s and early 1960s in Europe near the Allied posts of women in early pregnancy to take this drug to reduce the reaction to pregnancy, and later found that many of the fetus was born with a short upper limb, lower limb merger and seal-shaped so called seal-like malformation (sirenomelus), which was recognized in the earlier This is an early recognition of the class X drugs. The sex hormone stilbestrol, which was commonly used in the past, was used to treat preeclampsia in the early 50’s of the last century, and it was found that vaginal adenopathy or clear cell carcinoma of the vagina could occur in the offspring of females between the ages of 6 and 26 years old, and the consequences of this were serious, so it belonged to the X class of drugs. These are two famous cases of drug teratogenesis. Vitamin A can also be teratogenic when taken orally in large doses, which is also a class X drug, and retinoic acid, a derivative of vitamin A, is a kind of drug for treating skin diseases, which is also a class X drug. What is often overlooked is that heavy alcohol consumption, such as heavy drinking in early pregnancy, and the ingestion of large amounts of ethanol, 150 ml or more per day can cause fetal dysplasia or developmental malformations. Therefore, ethanol is classified by the FDA as Class D for small amounts of alcohol consumption and Class X for large amounts. In addition, sedative drugs such as flurazepam and flunitrazepam belong to Class X, and antitumor drugs such as aminopterin also belong to Class X. In summary, the use of ethanol during pregnancy can cause fetal dysplasia or malformation. In summary, the following points of attention are proposed for the use of drugs in pregnancy: (1) Use of drugs in pregnancy, avoid multiple drug prescriptions, and choose class A and B drugs as much as possible. (2) Instead of thinking only about medication, one should focus on the disease, which can pose additional risks to both mother and fetus. (3) Not only drugs can cause teratogenicity, but also note various other teratogenic possibilities, which should be carefully explained to the patient when administering drugs. (4) It should be noted that early pregnancy is the stage of differentiation of fetal body parts and organs, drug teratogenicity is prone to occur in this stage, the middle and late pregnancy medication safety increased, but some drugs, such as ethanol, the harm to the fetus, especially the nervous system, is throughout the entire stage of pregnancy. In addition, it should be noted that: before the 28th week of pregnancy, almost all drugs can pass through the placenta to reach the fetus, fertilization of the egg 3 to 8 weeks of the risk of drugs for teratogenicity or kill the embryo to cause miscarriage. 9 weeks into the fetal stage, the risk of drugs is toxicity to injure the function of organs. Therefore, if the mother’s disease to make the fetus infected should be selected safe, the fetus and amniotic fluid drug concentration and the mother close to the drug, in order to achieve the mother and child with the treatment; pregnant women do not casually use over-the-counter medicines, drugs should be taken under the direction of a doctor before use; drugs should be used in the smallest amount of the minimum effective amount of the shortest effective course of treatment, to avoid blindly large doses, long-term use; non-disease, try to avoid the use of drugs in the early stages of pregnancy.