Several tests are required by law or medical standards for every pregnant woman. It is important that any physician who cares for a pregnant woman know the results of these tests and act upon them if necessary.

The first and most important test is for pregnancy. Any woman of childbearing age should be considered pregnant unless there is evidence to the contrary if any medical treatment might affect the pregnancy or the fetus. Most radiology departments are covered in signs that ask women if they might be pregnant. Many internists, however, do not ask a woman about pregnancy and contraception before prescribing a drug that is not accepted for use in pregnancy. The risks, both medical and legal, are much greater for some drugs than they are for a chest X ray.

On the other hand, there is no laboratory test that can establish pregnancy beyond doubt. A physician should never tell a woman that she is or is not pregnant on the basis of a laboratory test alone. A history and physical examination are as necessary to making this diagnosis as any other. A patient who is assured that she is not pregnant may expose herself to agents that can harm her fetus. Even if there are no expected problems, failure to diagnose the pregnancy can interfere with the patient’s receiving proper prenatal care and will reduce her options about abortion or prenatal diagnosis.