Prenatal Tests

What to know about pregnancy ultrasound and other tests

Soon after getting the joyous news that you're expecting, you're going to have to start prenatal testing to ensure both you and your baby are healthy and safe. Prenatal tests begin during your first trimester, and will continue up until you're ready to deliver the baby. They include pregnancy ultrasounds, prenatal blood tests and other screenings that check for the possible presence of genetic conditions and evaluate the potential for complications.


Prenatal Testing: Common Procedures

During the first trimester of pregnancy, you'll have an NT pregnancy ultrasound as well as two prenatal blood tests that measure the levels of specific substances in your bloodstream. The NT or nuchal translucency ultrasound checks to see if any fluids are building up in the back of the fetus' neck (which can cause problems if they are). The blood tests look for plasma proteins and hormones called chorionic gonadotropins, both of which may cause chromosomal deficiencies if you have too much of them.

Later in your pregnancy, you will have to undergo further prenatal testing. Other procedures you'll encounter on your journey to motherhood include:

  • Chorionic villus sampling (CVS). The CVS test is done fairly early in your pregnancy. During this procedure, a sample of your chorionic villi, which are tiny growths that are found in the placenta, is taken. The sample is then biopsied to check for problems which can signal the possibility of the baby having a genetic disorder. Your doctor will usually only order a CVS test if you or your father has a disease that you have a history of in your family.
  • Glucose screenings. These tests are done to check for the possibility of gestational diabetes. Some expectant moms develop diabetes that lasts for the duration of the pregnancy or, in rare cases, beyond. If you are having diabetic symptoms, your doctor will order glucose screenings.
  • Amniocentesis. This test analyzes a sample of the amniotic fluid in your placenta and can detect neural tube defects and certain chromosomal disorders.
  • Non-stress tests. These procedures are performed during the third trimester of pregnancy and measure the baby's movements and heart rate.

Some of the other prenatal tests you may encounter include alpha-fetoprotein screenings, genetic screenings and strep cultures. You will also have regular ultrasounds to ensure the fetus is developing in your womb normally.