I hope it will be helpful to talk about this today. To understand this section, it is important to familiarize yourself with the FDA’s grading standards for medications used in pregnancy and childbirth. FDA grading standards on drugs during pregnancy The FDA classifies drugs into five classes of A, B, C, D, and X according to their teratogenicity to the fetus: Class A: Demonstrated to be nonhazardous to the fetus in studies in humans with control groups. Includes multivitamins, vitamin preparations during pregnancy, but excludes high-dose vitamin preparations. Class B: No harm to the fetus has been demonstrated in animal studies, but no studies in humans are available; or adverse effects have been demonstrated in animal studies, but this effect has not been found in studies in humans with good control groups. Category C: No good animal or human studies are available, or adverse effects on the fetus have been demonstrated in animal studies, but there is a lack of available information in humans. Many drugs commonly used in pregnancy fall into this category. Category D: There is evidence of harm to the fetus, but the advantages and disadvantages should be weighed during pregnancy, and when the advantages outweigh the disadvantages, they can still be used. For example, phenytoinna and carbamazepine. Category X: The risk to the fetus has been shown to significantly outweigh any benefit. For example, isotretinoin, which is used to treat acne, can cause a variety of malformations of the fetal central nervous system, face and cardiovascular. 1, antibiotic drugs ① penicillin: B drugs, less toxic, is the safest anti-infective drugs for pregnant women, including broad-spectrum penicillin such as ampicillin, piperacillin, meloxicillin and other β-lactam preparations. ② Cephalosporins: Class B drugs. These drugs can pass through the placenta, but there are no reports of teratogenicity of such drugs, in pregnancy plasma half-life is shorter than non-pregnancy. They are available during pregnancy. Aminoglycosides: Class D or C drugs. This kind of drug is easy to pass through the placenta, umbilical blood drug concentration increased significantly, pregnant women and fetuses have a certain degree of harm, prohibited or used with caution during pregnancy. ④ Macrolides: mostly class B, due to large molecular weight, not easy to pass through the placenta. It can be used for penicillin allergy and chlamydia, mycoplasma infection. ⑤ Tetracyclines: mostly class D, including tetracycline (D), oxytetracycline (D), doxycycline (D), memantine (D) and so on. These drugs can easily pass through the placenta and into breast milk and are teratogenic. Tetracycline fluorescent substances can be deposited in tooth enamel and fetal bones, affecting fetal tooth enamel and physical development, leading to intrauterine growth retardation. When pregnant women with renal insufficiency, it can cause acute fatty liver in pregnant women, and is prohibited during pregnancy. The concentration of these drugs in breast milk is high, and it is necessary to weigh the advantages and disadvantages of using or suspending breastfeeding during breastfeeding. Chloramphenicol: it can pass through the placenta and enter the breast milk, it has inhibitory effect on bone marrow, and it can cause “gray baby syndrome” when used in preterm infants. It is prohibited during pregnancy and lactation. (vii) Quinolones: mostly class C drugs, including piperacid, haloperidol, ciprofloxacin, ofloxacin, sparfloxacin, etc. The mechanism of action of these drugs is to inhibit the DNA of bacteria. The mechanism of action of such drugs for the inhibition of bacterial DNA helicase, such drugs have a strong affinity for bone and cartilage, can cause irreversible arthropathy in animals, or affect the development of fetal cartilage, prohibited during pregnancy. ⑧ Sulfonamides: mostly class C, this type of drug is easy to pass through the placenta, animal experiments have a teratogenic effect, but there is no report in humans. Application in late pregnancy can make the newborn thrombocytopenia, hemolytic anemia. It can also competitively inhibit the binding of bilirubin to albumin, causing neonatal hyperbilirubinemia. Use with caution during pregnancy and prohibited before delivery. ⑨ Jejamycins: including Jejamycin, clindamycin, etc., are class B drugs. Can pass through the placenta and into the milk, no record of adverse effects on the embryo, relatively safe. ⑩ Metronidazole: now Class B, used to be classified as Class C. There are reports of 1,700 cases of early pregnancy after the application of women did not increase the rate of teratology, recently the FDA has been classified as a class B drug. The Centers for Disease Control and Prevention (CDC) has recommended its use in the treatment of vaginal trichomoniasis during pregnancy. However, tinidazole is a class C drug, used with caution during pregnancy. Ornidazole: animal experiments are not teratogenic, but there is no controlled study in pregnant women, use with caution. 2, antiviral drugs ① Ribavirin (virus azole): that is, triazolyl nucleoside, for the X class of drugs, animal experiments found that almost all kinds of test animals after the application of this product, there are teratogenicity and embryocidal effect, contraindicated during pregnancy. The elimination of this product in the body is very slow, four weeks after stopping the drug can not be completely removed from the body. Acycloguanosine: Acyclovir, a class B drug. This product can inhibit DNA synthesis, used for herpes virus infection. There are reports: 581 cases of pregnancy with this drug, the incidence of malformation did not increase. Vanadolovir: Class B; Ganciclovir: Class C. ③ Interferon: best not used during pregnancy. ④ Lamivudine, Zidovudine: Class C, can be used in the treatment of AIDS during pregnancy. 3.Anti-tuberculosis drugs ① Isoniazid: Class C drug. This drug has high lipid solubility, low molecular weight, and hardly binds to plasma proteins, so it is easy to pass through the placenta, and the concentration in umbilical cord blood is higher than that in mother’s blood. However, a retrospective analysis of 4900 pregnant women using isoniazid showed no increase in the rate of fetal malformations, and it is now considered to be available to pregnant women with tuberculosis. ② Rifampicin: Class C drug. Animal experiments found that the application of RFP to pregnant rats and mice, the fetus can develop spina bifida and cleft palate. However, it has been reported that in 204 cases of patients using rifampicin during pregnancy, the rate of neonatal malformations did not increase. It is a cautionary use during pregnancy. However, the concentration of the drug in breast milk is low, and can be used during lactation. Ethambutol: Class B drug. It is currently believed that this product has no teratogenic effect on humans, and is preferred during pregnancy when suffering from tuberculosis. 4, antifungal drugs mycotoxin and clotrimazole, are class B drugs, available during pregnancy. Miconazole and fluconazole are class C drugs. Disomycin B is used to treat systemic mycobacterial infections, and no increase in congenital malformations has been reported. Etraconazole (C) lacks studies in early human pregnancy and is used with caution during pregnancy. High doses of fluconazole can cause fetal malformations in animals, but no human pregnancy teratogenicity has been reported.