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Pronunciations angiotensin isotretinoin lithium methotrexate placenta previa teratogen thalidomide tretinoin uterus warfarin

During pregnancy, a problem may occur or a condition may develop to make the pregnancy high risk. For example, pregnant women may be exposed to something that can cause birth defects (teratogens), such as radiation, certain chemicals, drugs, or infections. Or a disorder may develop. Some disorders are related to (are complications of) pregnancy.

Drugs

Some drugs taken during pregnancy cause birth defects—see Drug Use During Pregnancy). Examples are isotretinoin Some Trade Names
ACCUTANE
(used to treat severe acne), some anticonvulsants, lithium Some Trade Names
LITHANE
LITHONATE
, some antibiotics (such as streptomycin, kanamycin Some Trade Names
KANTREX
, and tetracycline Some Trade Names
ACHROMYCIN V
TETRACYN
SUMYCIN
), thalidomide Some Trade Names
THALOMID
, warfarin Some Trade Names
COUMADIN
, and angiotensin-converting enzyme (ACE) inhibitors (if taken during the last two trimesters). Taking drugs that block the actions of folate (folic acid), such as the immunosuppressant methotrexate Some Trade Names
RHEUMATREX
or the antibiotic trimethoprim Some Trade Names
PROLOPRIM
TRIMPEX
, can also cause birth defects. A deficiency of folate increases the risk of having a baby with a birth defect. Early in pregnancy, women are asked if they are using any of these drugs.

Women are also asked if they use any recreational drugs. Of particular concern are alcohol, cocaine, and nicotine Some Trade Names
NICORETTE
NICOTROL
(in cigarette smoking). All of these drugs can cause miscarriage or cause the baby to be underweight or to have birth defects. These drugs have the following risks:

• Alcohol: The risk of mental retardation is increased. Fetal alcohol syndrome is also possible (see Drug Use During Pregnancy: Alcohol).
• Cocaine: The risk of premature detachment of the placenta (placental abruption), premature birth, and stillbirth is increased. The fetus may not grow as much as expected.
• Smoking cigarettes: The risk of stillbirth and pregnancy complications, such as premature labor, placenta previa, placental abruption, and premature rupture of membranes, is increased. The fetus may not grow as much as expected, and children are more likely to have behavioral problems and mental retardation.

Disorders That Develop During Pregnancy

During pregnancy, women may develop disorders that are not directly related to pregnancy (see Pregnancy Complicated by Disease). Some disorders increase the risk of problems for pregnant women or the fetus. They include disorders that cause a high fever, infections, and disorders that require abdominal surgery. Certain disorders are more likely to occur during pregnancy because of the many changes pregnancy causes in a woman's body. Examples are thromboembolic disorders, anemia, and urinary tract infections.

Pregnancy Complications

Pregnancy complications are problems that occur only during pregnancy (see Pregnancy Complications). They may affect the woman, the fetus, or both and may occur at different times during the pregnancy. For example, complications such as a mislocated placenta (placenta previa) or premature detachment of the placenta from the uterus (placental abruption) can cause bleeding from the vagina during pregnancy. Women who have heavy bleeding are at risk of losing the baby or of going into shock and, if not promptly treated, of dying during labor and delivery.

Last full review/revision December 2008 by Christian M. Briery, MD; John Morrison, MD