Multiple Pregnancy: Twins or More - Exams and Tests
multiple pregnancies are now identified during the
first or second
fetal ultrasound can show whether there is more than
one fetus in the uterus. If you have more than one fetus, you will have an
ultrasound several times during the pregnancy to monitor fetal growth and
Sometimes the first sign
of a multiple pregnancy is from a test that was done for another reason. For
example, a very high level of
human chorionic gonadotropin (hCG), the "pregnancy
test" hormone, can be a sign of multiple pregnancy.
Tests used during a multiple pregnancy
Tests used to check for birth defects
Fetuses in multiple pregnancies have an increased risk of
genetic disorders and birth defects.
There are two types of birth defects tests: screening and diagnostic.
Screening tests show the chance that a baby has a certain birth defect. But they can't tell you for sure that your baby has a problem. Some of the available screening tests for birth defects are not as accurate when used for women carrying more than one baby. Talk to your doctor about your options for screening tests.
Diagnostic tests show if a baby has a certain birth defect. Diagnostic test
options may include:
- Chorionic villus sampling (CVS). It uses a tiny piece
placenta, taken by passing a thin tube through your
vagina and cervix and into the uterus. The sampling and genetic testing are
done between 10 and 12 weeks of pregnancy.
- Amniocentesis, which uses a small amount of amniotic
fluid, taken by inserting a needle into your abdomen and uterus. The sampling
and genetic testing are usually done between 15 and 20 weeks of pregnancy.
(Amniocentesis is also sometimes used in the last trimester to see whether the
fetuses' lungs are mature enough to breathe well after delivery.)
CVS and amniocentesis have the same slight
miscarriage risk when used to test a multiple
pregnancy. You may
want earlier CVS results if you have to make decisions about treating or
continuing a pregnancy.
For more information, see the topic
Birth Defects Testing.