As society advances, it brings with it an increasing incidence of malformed children incompatible with progress, which is related to the older age of pregnant women, environmental pollution, excessive competitive pressure, and medication use during pregnancy. Drugs can act directly on the fetus through the placental barrier or indirectly through maternal physiology. Improper use of drugs during pregnancy can cause damage to the embryo, including miscarriage, teratogenicity, growth retardation, as well as visual and hearing defects, behavioral abnormalities, etc., while interfering with fetal development and teratogenicity is related to the dose of drugs, the time of administration and the permeability of the placenta. The following is the author’s application principles for the use of drugs in pregnant women. In order to ensure the safety of pregnant women and fetus, in principle, pregnant women should avoid using any drugs. However, when there are diseases that endanger the health or life of pregnant women, they should be used after fully weighing the pros and cons, and the dose should be adjusted at any time according to the condition of the drug, and the drug should be stopped in time, and the blood concentration should be monitored when necessary. 2, available during pregnancy can be used without drugs as far as possible Pregnant women use drugs directly related to the physical and mental health of the next generation. In different stages of fetal development, its organ function is not yet perfect, such as improper use of drugs, will have adverse effects, in the late 1850s, early pregnancy after taking thalidomide (response to stop) nearly 10,000 cases of seal teratology, causing worldwide attention to the teratogenic effects of drugs, women in pregnancy even vitamin drugs should not be used in large quantities, so as not to have adverse effects on the fetus, for example Large amounts of vitamin A during pregnancy can lead to skeletal abnormalities or congenital cataracts in the fetus; another example is that excessive vitamin D can lead to mental retardation and aortic stenosis in the fetus. In the early stages of pregnancy, if it is only to relieve general clinical symptoms or if the condition is mild enough to allow postponement of treatment, then postpone treatment until the middle or late stages of pregnancy. Thalidomide can cause malformation of fetal limbs, ears and internal organs; estrogen, progesterone and androgen often cause abnormal fetal sex development; folic acid antagonist (methotrexate) can cause cranial and facial malformation, cleft palate, etc.; alkylating agents such as nitrogen mustard can cause genitourinary system abnormalities, finger and toe malformations; alkylating agents such as methotrexate can cause fetal malformation. Other drugs such as anti-epileptic drugs (phenytoin sodium, trimethoprim, etc.), anticoagulants (warfarin), alcohol, etc. can cause malformations. 4, the use of drugs must have clear indications, and to choose drugs that are not harmful to the fetus To do this, we must understand the impact of drugs on the fetus during different periods of pregnancy, and try to use drugs that are safe for pregnant women and fetuses, in the process of medication should pay attention to the duration of medication should be short rather than long, and the dose should be small rather than large. The units with conditions should pay attention to the determination of drug blood concentration, so that the dose can be adjusted in time, so that the target organs can obtain effective drug concentration, but also to ensure that the drug concentration in the fetus is not too high. Any new drugs belonging to the clinical verification, as well as drugs with uncertain efficacy should not be used for pregnant women. 5, the use of drugs should be strictly control the dose and duration of drugs such as a case of hypertension patients, with 25% magnesium sulfate injection 20 ml intramuscular injection, the fetus delivered after rescue, but maternal death (this product is used for hypotensive, eclampsia, uremia, etc., intramuscular injection should control the dose). 6, to be careful with the use of drugs that can cause uterine contractions posterior pituitary gland, contraction agents such as contraction of the uterus in small doses can make the uterus paroxysmal contractions, large doses can make the uterus tonic contractions, contraindications to contraction of the uterus absolutely can not be applied, the maternal suitable for contraction of the uterus, the application should also be particularly cautious, if the uterus is found to contract too strong, too often, or fetal heart is not good, should be immediately discontinued, ergotamine, ergot The new alkali can also cause tonic contractions of the uterus, and its effect is also more lasting, mainly used clinically for postpartum hemorrhage, but this drug is prohibited before the delivery of the fetus, otherwise it can cause intrauterine asphyxia. 7, to weigh the pros and cons, never abuse antibacterial drugs during pregnancy For pregnant women suspected of infection, detailed clinical examination and bacteriological examination must be carried out, if necessary, the isolated pathogenic bacteria for drug sensitivity testing, preferably based on the results of drug sensitivity testing for drug selection, suspected fungal infection, fungal culture should be done. When the causative organism is not yet clear, antibacterial drugs can be selected on the basis of clinical diagnosis, and the principle is that the advantages and disadvantages to the patient should be considered first, and attention should be paid to the impact on the fetus. For patients with severe infections where the causative organism is unknown, a combination of drugs is appropriate, generally using high doses of penicillin or second or third generation new penicillin or cephalosporin and gentamicin (note that gentamicin is absolutely used for intravenous injection). This combination has a good antibacterial effect on most of the pathogenic bacteria that are commonly infected during pregnancy or postpartum. If anaerobic genus infections are suspected, antimicrobials effective against anaerobic bacteria may be used. Metronidazole is effective against common weak anaerobic bacillus infections and can be tried, but should not be applied in the first 3 months of pregnancy. 8, pregnancy medication must consider the “after-effects” such as taking the contraceptive pill, should stop taking 3 months before pregnancy, late pregnancy medication, should consider the impact of maternal breastfeeding on the newborn. 9, try not to use drugs before delivery Some drugs taken in late pregnancy can compete with bilirubin protein binding sites, causing an increase in free bilirubin, which can easily lead to neonatal jaundice. Some drugs are easy to pass through the fetal blood-brain barrier, leading to intracranial hemorrhage in newborns, so care should be taken to stop the drugs 1 week before delivery. 10, pregnancy medication should be used under the guidance of a doctor, pay attention to the adverse effects of drugs The first three months of pregnancy there are drugs that are absolutely avoided, drugs that are used only when necessary, drugs that are avoided or reduced as much as possible, 4 to 9 months of pregnancy there are drugs that are completely avoided, there are only drugs that are used according to medical advice. During pregnancy, it should be noted that aminoglycoside antibiotics can cause permanent deafness in the fetus; tetracycline after 5 months of pregnancy can cause yellowing of the baby’s teeth, underdevelopment of tooth enamel and impaired bone growth; thiazide diuretics can cause stillbirth and fetal electrolyte disturbance; chloroquine can cause optic nerve damage, mental retardation and convulsions; long-term application of chlorpromazine can cause retinopathy in infants; antithyroid drugs such as thiouracil, The long-term application of chlorpromazine can cause retinopathy in infants; antithyroid drugs such as thiouracil, tapazole and iodine can affect fetal thyroid function, leading to stillbirth, congenital hypothyroidism or fetal goiter, and even compression of the airway causing asphyxia; excessive intake of vitamin D by pregnant women can lead to high blood calcium, mental retardation, renal or small pulmonary artery stenosis and hypertension in newborns; lack of vitamin A during pregnancy can cause neonatal cataracts; application of chloramphenicol before delivery can cause neonatal circulatory disorders and The use of aspirin in late pregnancy can cause overdue pregnancy, prolonged labor and postpartum hemorrhage, while the use of acetaminophen has no adverse effects, so when pregnant women need antipyretic and analgesic drugs, acetaminophen can be used instead of aspirin. Then again, quinolones are absolutely forbidden for women in the perinatal period. In addition to the above points, as a clinician should also be aware of the U.S. FDA promulgated the five levels of drug risk to pregnancy criteria. class A: no adverse effects on the fetus, the risk is very small; class B: animal experiments have not been seen on the fetus, but the safety in humans lack of clinical control studies, a variety of clinical use of drugs belong to this category; class C: animal experiments found in the fetus still have adverse effects, but the safety in humans Class D: harmful to the fetus, but in the clinical importance, and no alternative drugs, should be used after fully weighing the pros and cons; Class X: has been confirmed to have teratogenic effects on humans, extremely harmful, prohibited. Therefore, we should keep abreast of the situation, carefully study the changes in drug applications, pay attention to the collection of pharmacy information, moreover, we should abide by professional ethics and should never be influenced by the current unethical practices.