in pharmacodynamic aspects, that is, the response of the fetus to drugs, with the newborn and children, there are no great differences, but the area of pharmacokinetics has a special point:

(1) the majority of drug transit through the placenta into the fetal body:

(2) fetal liver, brain and other relatively large blood flow more than 60% of blood flow into the liver, the intrahepatic distribution of more drugs, liver metabolism is very low, the fetus of drug and the glucuronic acid combined with the lack of capacity, so some combination of detoxification through the liver of drug poisoning easy. Poor fetal blood-brain barrier function, drug easy access to their central nervous system affected. Fetal plasma protein than the parent low, can increase the free drug.

(3) fetal renal function of excretion of drugs caused by poor fetal drug accumulation in vivo. Therefore, the drug can affect the fetal brain, nervous system, external genital development. pregnant women in the last week of pregnancy when the drug should pay particular attention to, because some drugs on the fetus in childbirth would have serious adverse reactions, and the fetus as a newborn baby must be fully responsible for drug metabolism and elimination of the burden. But this time the baby's metabolic system is imperfect can not be dealt with promptly and efficiently, and the elimination of drugs, so drugs can accumulate in the infant and produce the performance of drug overdose. Metabolism in preterm infants is more immature, the danger will increase in direct proportion.

application in late pregnancy in the following drugs on the fetus are at high risk:

oral anticoagulant - allows intrauterine bleeding, still births and abortions;

antithyroid drug - allows fetal thyroid swelling, and even can cause neonatal asphyxia;

reserpine and propranolol - enable fetal bradycardia, and even the middle class in post-natal or neonatal circulatory disturbance occurred;

streptomycin and other aminoglycoside antibiotics - can damage the the eighth cranial nerve of the fetus;

isoniazid - Neonatal encephalopathy can occur;

tetracycline -- can affect the development of fetal bone and gums;

analgesics morphine addiction - allows fetal addiction.

In addition, phenol, progesterone, anabolic hormones, oral hypoglycemic drugs, and androgen hormones such as adrenal cortex, the latter part of pregnancy caused by uterine contraction can be induced by drugs such as lysergic abortion bases, laxatives, quinine , quinidine have not applied.