In clinical practice, we often encounter maternal infectious diseases that require antibiotics. Many young clinicians are at a loss at this point, not knowing which anti-infective drugs to use and which not to use. That’s why Medical Voices is talking about this issue today, in the hope that it will be helpful. To understand this section, it is important to be familiar with the FDA’s classification criteria for maternal medications. FDA grading standards on drugs in pregnancy The FDA classifies drugs into five levels of harm to the fetus, A, B, C, D, and X, based on their teratogenicity to the fetus: Class A: proven to be harmless to the fetus in studies with controlled groups in humans. This includes multivitamins, vitamin preparations during pregnancy, but not high-dose vitamin preparations. Class B: proven harmless to fetuses in animal studies, but no studies in humans yet; or proven adverse effects in animal studies, but this effect was not found in studies with good control groups in humans. Class C: There are no good animal tests or studies in humans yet, or there are adverse effects on the fetus in animal tests, but there is a lack of available information in humans yet. Many drugs commonly used during pregnancy fall into this category. Category D: There is evidence of harm to the fetus, but the pros and cons should be weighed during pregnancy and can still be used when the benefits outweigh the harms. For example, phenytoinamide, carbamazepine, etc. Class X: The risks to the fetus have been shown to significantly outweigh any benefits. For example, isotretinoin for acne can cause a variety of malformations in the fetal central nervous system, face and cardiovascular. 1, antibiotic drugs: ① penicillin class: for class B drugs, less toxic, is the safest anti-infective drugs for pregnant women, including broad-spectrum penicillin such as ampicillin, piperacillin, melocillin 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, and the plasma half-life is shorter in pregnancy than in non-pregnancy. They are available during pregnancy. (3) Aminoglycosides: They are class D or C drugs. These drugs are easy to pass through the placenta, and the drug concentration in the umbilical cord blood increases significantly, which is harmful to the pregnant woman and the fetus, and is prohibited or used with caution during pregnancy. ④Macrolides: Most of them are class B. They are not easy to pass through the placenta because of their large molecular weight. It can be used for penicillin allergy and chlamydia and mycoplasma infection. ⑤ Tetracyclines: mostly class D, including tetracycline (D), hygromycin (D), doxycycline (D), melphalan (D), etc. Such drugs are easily passed through the placenta and into breast milk, and are teratogenic. Tetracycline fluorescent substances can be deposited in tooth enamel and fetal bone, affecting fetal tooth enamel and physical development, leading to intrauterine growth retardation. When a pregnant woman has 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 breastfeeding needs to be weighed against the advantages and disadvantages of using or suspending breastfeeding. (6) Chloramphenicol: It can pass through the placenta and enter the breast milk, has a suppressive effect on the bone marrow, and can cause “gray baby syndrome” when used in premature babies. It is prohibited during pregnancy and lactation. (7) Quinolones: Most of them are Class C drugs, including pyrazole, haloperidol, ciprofloxacin, ofloxacin, sparfloxacin, etc. The mechanism of action of these drugs is to inhibit bacterial DNA. The mechanism of action of such drugs is to inhibit bacterial DNA helicase, such drugs have a strong affinity for bone and cartilage, which can cause irreversible arthropathy in animals, or affect fetal cartilage development, prohibited during pregnancy. ⑧ sulfonamides: mostly C class, this class of drugs easily through the placenta, animal experiments have teratogenic effects, but no human reports. Application in late pregnancy can cause thrombocytopenia and hemolytic anemia in newborns. It can also competitively inhibit the binding of bilirubin and albumin, causing neonatal hyperbilirubinemia. Use with caution during pregnancy and forbidden before delivery. ⑨Jessamycin: including jessamycin, clindamycin, etc., is a class B drug. It can pass through the placenta and into breast milk, no record of adverse effects on the embryo, relatively safe. ⑩Metronidazole: Now it is class B, and it was classified as class C in the past. It has been reported that 1700 cases of early pregnancy did not increase the rate of malformation after application, and recently the FDA has classified it as a Class B drug. The CDC has recommended it for the treatment of vaginal trichomoniasis during pregnancy. However, tinidazole is a class C drug and should be used with caution during pregnancy. Ornidazole: no teratogenicity in animal experiments, but no controlled studies in pregnant women, so use with caution. 2. Antiviral drugs: ① Viridazole: triazolyl nucleoside, a class X drug, was found to be teratogenic and embryonic killing in almost all species of animals tested in animal experiments, and is prohibited during pregnancy. The elimination of this product in the body is very slow, and can not be completely removed from the body four weeks after stopping the drug. ②Acyclic guanosine: Acyclovir, a class B drug. It can inhibit DNA synthesis and is used for herpes virus infection. It has been reported that there was no increase in the incidence of malformations in 581 cases of this drug used during pregnancy. Wanairovir: Class B; Ganciclovir: Class C ③ Interferon: best not used during pregnancy ④ Lamivudine and Zidovudine: Class C, can be used for AIDS treatment during pregnancy. 3, anti-tuberculosis drugs: ① Isoniazid: for class C drugs. This drug has high lipid solubility, low molecular weight and almost no binding to plasma proteins, so it can easily pass through the placenta and the concentration in the umbilical cord blood is higher than that in the mother’s blood. However, a retrospective analysis of 4900 pregnant women using isoniazid showed no increase in the rate of fetal malformation, and it is now believed that it can be used in pregnancy with TB. ②Rifampicin: Class C drug. Animal studies have found that spina bifida and cleft palate can occur in fetuses when RFP is applied to pregnant rats and mice. However, in 204 patients who used Rifampicin during pregnancy, the rate of neonatal malformation was not increased. It is a cautionary use during pregnancy. However, the drug concentration in breast milk is low, so it can be used during lactation. (3) Ethambutol: Class B drug. At present, it is believed that this product has no teratogenic effect on human beings and is preferred in case of tuberculosis during pregnancy. 4, antifungal drugs: mycobacterium and clotrimazole, both class B drugs, available during pregnancy; miconazole, fluconazole for class C drugs; dicloxacillin B for the treatment of systemic mycobacterial infections, no increase in congenital malformations have been reported. Itraconazole (C) lacks studies in early human pregnancy, and should be used with caution during pregnancy. High doses of fluconazole can cause fetal malformations in animals, but no reports of teratogenicity in humans during pregnancy.