When pregnant women with bacterial infectious diseases need to use antibacterial drugs, clinicians are required to master the principle of action of the drug, antibacterial spectrum, dosage, toxicity and side effects, but also to be familiar with whether these drugs have an impact on the fetus, as well as the extent of the impact of the degree, the period of time; not only to achieve the purpose of curing the disease, but also to minimize the impact on the fetus. According to the degree of influence 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 can be used with caution during pregnancy and those that are prohibited during pregnancy, which are described as follows. Antibacterial drugs that can be used during pregnancy (Class B) Class B drugs are relatively safe and basically harmless to the mother and fetus. Penicillin antibiotics of this class of bactericidal principle is to hinder the synthesis of bacterial cell wall, mammals have no cell wall, so this class of antibiotics is the least toxic to the human body, and does not cause fetal malformation. However, its shortcomings are narrower antibacterial spectrum, unstable to the bacterial production of β-lactamase, easy to produce drug resistance, unstable to acid, can not be taken orally; easy to allergic reactions. But now put into use semi-synthetic, composite penicillin preparations have made up for these shortcomings from various aspects, both acid or enzyme resistance and broad-spectrum antibiotics, but also not easy to produce allergic reactions. Although the antimicrobial spectrum of each preparation is different, but the common point is not teratogenic effect. This class of drugs can be applied throughout pregnancy. Such as injectable penicillin sodium, oral Amorim capsules and so on. Cephalosporins (third generation) This class of antibiotics is very similar to penicillins and has a relatively small effect on the mother and fetus. What is more superior than penicillin is that its antibacterial spectrum is wide, it is stable to acid and β-lactamase produced by various bacteria, and the incidence of allergic reactions is low. The first generation of cephalosporins have a certain degree of nephrotoxicity, the second generation of nephrotoxicity is lower, the third generation of the kidneys has been basically non-toxic, pregnant women can be applied to the whole process of pregnancy. Such as cefoperazone sodium, ceftazidime sodium and so on. Macrolides This class of antibiotics is bacteriostatic, and the antibacterial spectrum is similar to that of penicillin. But it has its own characteristics: it is very useful for respiratory tract infections caused by general bacteria, and it is also effective for mycoplasma, chlamydia, toxoplasmosis, etc.; the blood concentration is not high, but the distribution of tissues and intracellular migration is good, low toxicity, and fewer metamorphoses should be used, so it is a safe use of antibiotics during pregnancy, and it can be applied during the whole process of pregnancy. These drugs, such as azithromycin, are preferred for pregnant women with penicillin allergy and respiratory tract infections. Anti anaerobic bacteria and anti-trichomoniasis drugs have been proved by animal experiments to have mutagenic effects on bacteria, so they are also dangerous to human beings. The first three months of pregnancy should be avoided, in order to prevent fetal malformation. Such as metronidazole, tinidazole. Antibacterial drugs used with caution in pregnancy (Class C) Class C drugs have only been shown to be teratogenic to the fetus or to kill the embryo in animal studies, but not in human studies have confirmed that pregnant women need to weigh the pros and cons of the use of drugs to confirm that the advantages outweigh the disadvantages of the application. Chloramphenicol antibiotics can be accumulated in the fetus through the placenta, because the fetus lacks glucuronosyltransferase in the liver, so the detoxification function of this type of drug is affected; late pregnancy, the use of newborns can be born with vomiting, anorexia, abdominal distension, and ultimately lead to circulatory failure, known as the “Gray Infant Syndrome”, so early pregnancy, mid-pregnancy, be careful! Therefore, it should be used cautiously in the early and middle stages of pregnancy, and prohibited in the late stages of pregnancy. The toxicity of quinolones is low, no teratogenic and mutagenic effects, but can cause joint lesions in young animals, affecting the development of cartilage; on the neuropsychiatric aspects also have an impact, so avoid the application of pregnancy. Such as haloperidol, ciprofloxacin and so on. Sulfonamides can enter the fetus through the placenta, and fetal blood bilirubin competition for plasma protein binding site, so that plasma free bilirubin increase, plasma free bilirubin for fat-soluble bilirubin, can penetrate the blood-brain barrier, resulting in fetal brain damage or neonatal jaundice after birth, therefore, avoid the application of gestation. Such as sulfadiazine, cotrimoxazole, etc.. Antibacterial herbs have the effect of direct excitation of uterine smooth muscle, so the amount can lead to preterm delivery, pregnant women should be used with caution; Panax quinquefolium and Panax quinquefolium belong to the same kind of plant, should also be used with caution. Antibacterial drugs prohibited in pregnancy (Class D) Class D drugs have definite evidence of harm to the fetus, unless the pregnant woman has an absolute effect after using the drug, otherwise do not consider the application. Aminoglycosides have ototoxicity and nephrotoxicity, with poor renal clearance and large individual differences in drug concentration, which can easily lead to an increase in blood drug concentration; the concentration of the drug in the inner ear lymphatic fluid is high. Infants (baby food) hearing impairment is mainly related to the amount of medication, and the relationship with the month of pregnancy is not large, but the incidence of 3% to 11%. This kind of drug is avoided during the whole process of pregnancy. The first time I saw the movie was when I was a kid, and it was the first time I saw the movie. Tetracyclines This class of drugs is typical of the drugs that cause fetal malformation. The use of early pregnancy can lead to fetal limb hypoplasia and short limb deformity; mid-pregnancy to tooth bud dysplasia, congenital cataracts; late pregnancy causes maternal liver failure, so the entire pregnancy should be banned tetracycline antibiotics. Such as tetracycline, oxytetracycline, etc. Erythromycin esterification of this class of antibiotics can lead to intrahepatic cholestasis and hepatic parenchymal damage in pregnant women, resulting in elevated aminotransferases, hepatomegaly and obstructive jaundice, etc., the incidence of which is as high as 40%, which may be associated with esterification of the hypersensitivity reaction, the class of drugs to avoid the application of the whole process of pregnancy. Such as erythromycin (odorless erythromycin), erythromycin ethylsuccinate and so on. Antibacterial Chinese (adult) medicine Andrographis paniculata can oppose progesterone, inhibit chorionic trophoblast production, can lead to miscarriage, early pregnancy is prohibited. Liushen Pill is a heat-clearing and swelling-reducing drug, its active ingredient is toadstool and musk, which can cause uterine contraction, causing miscarriage or preterm labor, so it is prohibited for pregnant women. The basic principles of medication in pregnancy 1, the correct choice of drugs that are not harmful to the fetus and the most effective for the disease suffered by the pregnant woman. 2, can use a drug to avoid joint use of drugs, can use the efficacy of the old drugs to avoid the use of new drugs have not yet been determined to have an adverse effect on the fetus, can use a small dose of drugs to avoid using large doses of drugs. 3, pregnant women must be used in emergency situations, but also should try to use the clinically verified for many years without teratogenic effect of the A, B drugs (A class of drugs, the use of safe, on the mother and the fetus health (health food) without adverse effects). 4, according to the size of the gestational week that the fetus belongs to the development period to consider the use of drugs, such as pregnancy within 3 months is the important period of fetal organ development, the use of drugs to be particularly cautious, can be postponed treatment, try to postpone to this period later. 5.According to the different degree of influence of drugs on the fetus, choose the drugs that have the least influence on the fetus. For example, if a pregnant woman is combined with hyperthyroidism, the order of selection of drugs is as follows: tranquilizers (Valium), beta-blockers (amiloride), anti-thyroid metabolism drugs (propylthiouracil). 6, should try to avoid unnecessary medication during pregnancy, including health care (health food) products. It has been reported in Hong Kong that ginseng saponin, the main active ingredient of ginseng, has a teratogenic effect on rat embryos, and it is recommended that ginseng should be used with caution during the first 3 months of pregnancy. It has been reported abroad that licorice can stimulate the manufacture of prostaglandins in pregnant women, which can lead to preterm labor and should be used with caution in early pregnancy. 7, in order to prevent drug-induced fetal malformation, in the first 3 months of pregnancy, in order not to use C, D type of drugs is good. In the third month of pregnancy after the use of class C drugs also need to weigh the pros and cons, to confirm that the advantages outweigh the disadvantages before application. In general, the use of class D drugs during pregnancy is prohibited. 8, pregnant women in rescue, special circumstances, the use of C, D drugs, should be given “warning”. Such as serum products caused by anaphylaxis, given calcium gluconate (Class A), paracetamol (Class B) is ineffective, had to use isoprinosine (Class C), dexamethasone (Class D) and other drugs, so as to effectively control the condition. There are also antiepileptic drugs for pregnant women with epilepsy (Class D), frequent seizures during pregnancy itself is very damaging to the mother and fetus, so in order to control the seizures have to use drugs; but the dose should be adjusted to the smallest possible dose to control the condition of seizures. Pregnant patients receiving aminoglycosides (class D), vancomycin, chloramphenicol, sulfonamides, flucytosine (class C) must be monitored for blood levels to minimize drug side effects.