Many drugs cross the placenta, but only some of them can have an adverse effect on the fetus because of the immature fetal metabolism and slower excretion rates. Waste products are excreted into the amniotic fluid and then absorbed by the mother or swallowed by the fetus.
Alcohol, barbiturates, and narcotics—such as diphenhydramine (Benadryl), amobarbital (Amytal), diazepam (Valium), codeine, heroin, methadone, morphine, propoxyphene (Darvon)—that are used during pregnancy can lead to harmful effects on the newborn. Use of these drugs during pregnancy can create an addiction in the newborn. The baby will go into withdrawal from the drug when they are born. This can result in hyperactivity, crying, irritability, seizures and even sudden death.
When taken by the mother during the first trimester, some drugs have a ter-atogenic effect on the fetus resulting in fetal defects. This includes mutagenic (genetic mutation) or carcinogenic (causing cancer) effects. These drugs include Thalidomide, which causes abnormal limb development, and cocaine, which causes miscarriages, fetal hypoxia (lack of oxygen), low-birth-weight infants, tremors, strokes, increase in stillbirth rates, congenital heart disease, skull defects, and other malformations.
Adverse side effects of the drug on the fetus can be avoided by carefully checking the Pregnancy Category of the medication before the medication is administered to a pregnant woman. Regardless of the Pregnancy Category of the drug, always carefully observe the pregnant patient after administering medication to assure that the patient doesn't show any observable adverse response.
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