When bacterial infectious diseases in women during pregnancy require antibacterial drugs, clinicians are required to master the principle of action, antibacterial spectrum, dosage, toxic side effects, as well as to be familiar with whether these drugs have an impact on the fetus, and the degree and period of impact; both to achieve the purpose of curing the disease, but also to minimize the impact on the fetus. According to the degree of impact of antibacterial drugs on the fetus and the toxic effects on the mother, they are divided into three categories: those that can be used during pregnancy, those that are used with caution during pregnancy and those that are prohibited during pregnancy, which are described below. The antimicrobial drugs that can be used during pregnancy (Class B) Class B drugs are safe and basically harmless to the mother and fetus. 1, penicillin class The bactericidal principle of this class of antibiotics is to hinder the synthesis of bacterial cell wall, mammals do not have a cell wall, so this class of antibiotics is the least toxic to humans and does not cause fetal malformation. However, its disadvantages are narrow antibacterial spectrum, unstable to β-lactamase produced by bacteria, easy to produce resistance, unstable to acid, can not be taken orally; prone to allergic reactions. However, the semi-synthetic and compound penicillin preparations now in use have made up for these disadvantages in many ways, being both acid- or enzyme-resistant and broad-spectrum antibiotics, and also less likely to produce allergic reactions. Although the antimicrobial spectrum of each agent varies, the common denominator is the absence of teratogenic effects. This class of drugs can be used throughout pregnancy. For example, injectable penicillin sodium, oral amoxicillin, etc. Cephalosporins (third generation) This class of antibiotics is very similar to penicillins and has less effect on the mother and fetus. It is superior to penicillins in that it has a broad antibacterial spectrum, is stable to acids and β-lactamases produced by various bacteria, and has a low incidence of allergic reactions. The first generation of cephalosporins has certain nephrotoxicity, the second generation has lower nephrotoxicity, and the third generation has basically no toxicity to the kidney, and can be applied during the whole pregnancy. Such as cefoperazone sodium, ceftazidime sodium, etc. 2, macrolides this class of antibiotics are antibacterial agents, antibacterial spectrum and penicillin similar. But it has its own characteristics: it is useful for respiratory infections caused by general bacteria, and it is also effective for mycoplasma, chlamydia, toxoplasma, etc. The blood concentration is not high, but the tissue distribution and intracellular migration is good, the toxicity is low, and the metamorphosis should be less, so it is an antibiotic that can be used safely during pregnancy, and it can be applied during the whole pregnancy. Pregnant women who are allergic to penicillin combined with respiratory tract infections can prefer these drugs, such as azithromycin. Anti-anaerobic and anti-trichomonas drugs These drugs have been proven by animal experiments to have mutagenic effects on bacteria, so they are also dangerous to humans. They should be avoided during the first 3 months of pregnancy to prevent fetal malformations. For example, metronidazole and tinidazole. Antimicrobial drugs used with caution during pregnancy (Class C) Class C drugs are only proven to be teratogenic to the fetus or can kill the embryo in animal experimental studies, but not in human studies. 1, chloramphenicol class This class of antibiotics can accumulate in the fetus through the placenta, because the fetus livers lack glucuronosyltransferase, so the detoxification function of this class of drugs is affected; late pregnancy drug neonates can be born after vomiting, anorexia, abdominal distension, and eventually can lead to circulatory failure, known as the “gray baby syndrome”, so early and mid-pregnancy The use of caution, late pregnancy is prohibited. 2, quinolones The toxicity of these drugs is low, no teratogenic mutagenic effects, but can cause arthropathy in young animals, affecting cartilage development; neuropsychiatric effects, so avoid the application during pregnancy. Such as haloperidol, ciprofloxacin, etc. Sulfonamides can enter the fetus through the placenta and compete with fetal blood bilirubin for the binding site of plasma proteins, resulting in an increase in plasma free bilirubin, which is a fat-soluble bilirubin and can penetrate the blood-brain barrier, causing fetal brain damage or neonatal jaundice after birth, so avoid application during pregnancy. Such as sulfadiazine, cotrimoxazole, etc. 4, antibacterial herbal medicine Da Qing Ye has a direct excitation of the smooth muscle of the uterus, so a large amount can lead to premature delivery, pregnant women should be used with caution; Ban Lan Gen and Da Qing Ye are similar plants, should also be used with caution. Antimicrobial drugs prohibited during pregnancy (Class D) Class D drugs have definite evidence of harm to the fetus, unless the pregnant woman has absolute effect after the use of drugs, otherwise do not consider the application. 1. Aminoglycosides have ototoxicity and nephrotoxicity, poor renal clearance, large individual differences in drug concentrations, and easy to cause elevated blood concentrations; high drug concentrations in the lymphatic fluid of the inner ear. Hearing impairment in infants is mainly related to the amount of medication used, not much related to the month of pregnancy, but its incidence is 3% to 11%. This class of drugs is avoided during the whole pregnancy. Such as streptomycin, kanamycin, etc. 2, tetracycline class This class of drugs is a typical fetal malformation drugs. The use of early pregnancy can lead to fetal limb dysplasia and short limb deformity; mid-pregnancy to dental bud dysplasia, congenital cataract; late pregnancy caused by maternal liver failure, so the entire pregnancy should be prohibited tetracycline antibiotics. Such as tetracycline, oxytetracycline, etc. 3, erythromycin esterified substances This class of antibiotics can lead to intrahepatic cholestasis and liver parenchymal damage in pregnant women, causing increased transaminases, hepatomegaly and obstructive jaundice, the incidence of up to 40%, which may be related to the hypersensitivity reaction of esterified substances, this class of drugs to avoid the application of the whole process of pregnancy. Such as etoricoxib (odorless erythromycin), erythromycin amber, etc. 4, antibacterial Chinese (into) drugs Andrographis can be antagonistic to progesterone, inhibit chorionic trophoblast production, can lead to miscarriage, early pregnancy is prohibited. Liushenwan is a heat-clearing and anti-swelling drug, the active ingredient of which is toadstool and musk, which can cause uterine contraction and miscarriage or premature delivery, and is therefore prohibited for pregnant women. The basic principles of medication during pregnancy: 1. correctly choose the drug that does not harm the fetus and is the most effective for the disease suffered by the pregnant woman. 2, can use a drug to avoid the combination of drugs, can use the efficacy of the old drugs to avoid the new drugs have not been determined to have adverse effects on the fetus, can use small doses of drugs to avoid using large doses of drugs. 3, when pregnant women have to use drugs in emergencies, they should try to use A and B drugs that have been clinically proven to have no teratogenic effects for many years (A drugs are safe to use and have no adverse effects on maternal and fetal health). 4, according to the size of the pregnancy week, that is, the fetus belongs to the development period to consider the use of drugs, such as within the third month of pregnancy is an important period of fetal organ development, the use of drugs should be particularly careful, can postpone treatment, as far as possible to postpone to this period. 5.According to the different degrees of influence of drugs on the fetus, we should choose the drugs with the least influence on the fetus. For example, if a pregnant woman is combined with hyperthyroidism, the order of drug selection should be: sedative (Valium), beta-blocker (Aminocardia), and anti-thyroid metabolizer (propylthiouracil). 6. Unnecessary medication, including health products, should be avoided as much as possible during pregnancy. In Hong Kong, it has been reported that ginsenoside, the main active ingredient of ginseng, has teratogenic effects on rat embryos, and women are advised to use ginseng with caution during the first three months of pregnancy. It has been reported abroad that licorice can stimulate the production of prostaglandins in pregnant women, which can cause premature delivery, so it should be used with caution in early pregnancy. 7. In order to prevent drug-induced fetal malformation, it is better not to use C and D drugs in the first 3 months of pregnancy. After the third month of pregnancy, the use of class C drugs should also be weighed against the advantages and disadvantages, to confirm that the benefits outweigh the disadvantages before application. In general, the use of Class D drugs is prohibited during pregnancy. 8, pregnant women in rescue, special circumstances, the use of class C, D drugs, should be given a “warning”. For example, if the anaphylactic shock caused by serum products, when calcium gluconate (class A) and paracetamol (class B) are not effective, you have to use promethazine (class C) and dexamethasone (class D), etc., so as to effectively control the condition. There are also anti-epileptic treatment drugs (Class D) for pregnant women with combined epilepsy. Frequent seizures during pregnancy are damaging to the mother and fetus, so drugs have to be used to control seizures; however, the dose should be adjusted to the minimum dose to control the seizures. Blood levels must be monitored when pregnant patients are treated with aminoglycosides (Class D), vancomycin, chloramphenicol, sulfonamides, and flucytosine (Class C) to reduce drug side effects.