A User's Guide to Prenatal Tests
I must confess -- before I became pregnant, I was a medical wimp. A finger
prick before my wedding day and annual checkups and pap smears were the extent
of my relationship with doctors, and I liked it that way. But my first prenatal
exam changed all that.
I soon discovered that no matter how young or healthy, moms-to-be face a
variety of prenatal tests to monitor the health of their babies and their
pregnancies. In most cases, these tests offer reassurance that everything is
going smoothly, and many of them are meant to spot problems, such as iron
deficiency or diabetes, that can be treated before complications occur.
Other tests, particularly those that are used to detect genetic problems,
such as Down syndrome, cystic fibrosis or spina bifida, can present some tough
choices and worries for parents-to-be. The initial screening tests are not
meant to be conclusive. They are intended to determine if you are at
higher-than-usual risk and may call for additional diagnostic tests that carry
some risk to the fetus, although the odds of a healthy baby are still high --
only about 2% to 3% of all babies are born with a genetic defect.
To decide which of these tests are right for you, it's important to
carefully discuss with your doctor or midwife what these tests are supposed to
measure, how reliable they are, the potential risks, and your options and plans
if the results hold bad news, says Dr. Michael Mennuti, chairman of obstetrics
at the University of Pennsylvania School of Medicine.
"If a woman and her partner say they wouldn't do anything differently if
the test showed a problem, then the value of a diagnostic test like
amniocentesis or chorionic villi sampling (CVS) isn't there," Dr. Mennuti
says. The test might be worthwhile, however, if a couple would consider
terminating the pregnancy or simply wants to prepare for a child with special
needs, he adds.
Here's a look at the most common prenatal tests you might undergo over the
next nine months. Some tests, such as urine or blood tests, might be repeated
during your pregnancy, as will routine blood pressure screening. Others, such
as CVS and amniocentesis, may not be offered unless your age or other factors
indicate that you or your baby are at higher risk for certain conditions or
First Trimester Tests
Here are some tests you may undergo during the first trimester of your
Blood tests: During one of your initial exams, your doctor or midwife
will identify your blood type and Rh factor, measure the level of iron in your
blood, check for immunity to rubella (German measles), and test for hepatitis
B, syphilis and HIV. Depending on racial, ethnic or family background, you may
be offered tests and genetic counseling to assess risks for diseases such as
Tay-Sachs, canavan, cystic fibrosis, thalassemia and sickle-cell anemia (if
these weren't done at a preconception visit).