Understanding Routine Tests During Pregnancy

When you’re pregnant, you go to the doctor a lot. You’re poked and prodded and your stomach is measured. You’re weighed at every visit (unfortunately!) and your blood pressure is closely monitored. As the weeks go on, you’ll undergo several tests. Hopefully you have a doctor that will thoroughly explain the reasons for each test and what the results may tell you but if you don’t, here is some information to help you on your pregnancy journey:

Blood Tests

If your health-care provider doesn’t already know the details about your blood, he or she will draw some blood early in the pregnancy. The blood will be taken from a vein on the inside bend of your elbow. This blood will tell a lot about…

  • Your blood group: A, B, or O. This information is important in case a blood transfusion is ever necessary.
  • Your rhesus (Rh) blood group: Your Rh factor may be negative or positive. The difference means nothing unless you are negative and the baby’s father is positive. In this case, your baby may be incompatible with your rhesus blood group, which can cause problems with future pregnancies. Knowing your blood type in advance lets your doctor prevent any trouble from occurring.
  • Hemoglobin levels. Hemoglobin keeps red cells filled with oxygen. Hemoglobin levels often fall during pregnancy, causing anemia; your doctor will want to make sure your levels don’t go too low.
  • Your immunity to rubella (German measles): If you have not built up an immunity to this disease, you will be cautioned to avoid exposure, especially during the first trimester.
  • STDs: Because sexually transmitted diseases can cause many problems for the developing fetus and newborn, your blood will be tested for hepatitis B, HIV, and syphilis.

Glucose Screening

Most expectant moms are given a glucose-screening test between Weeks 24 and 28 of the pregnancy to check for gestational diabetes.

You are at risk for developing gestational diabetes if you fit into any of these categories:

  • You have had gestational diabetes during an earlier pregnancy.
  • You have previously delivered a very large baby.
  • You are greatly overweight (approximately 20 percent over ideal body weight).
  • You are over 35.
  • You have high blood pressure.
  • You have a parent or sibling who is a diabetic.

The test for gestational diabetes is not painful. It is long, however. To take the glucose screening test you will drink a sugar solution (which tastes like a thick, flat cola—I’m not saying it’s delicious, but it’s not all that awful either). An hour later, a blood sample will be taken and the blood sugar level will be checked. If the reading is abnormal (which occurs about 20 percent of the time) you’ll go home and come back at a later date for a diagnostic exam, called a three-hour glucose tolerance test, to verify the results. If you get a high sugar reading on the first test, don’t get too worried. Approximately 85 percent of those with a positive result on this screening test show normal blood sugar levels in the glucose tolerance test.

If you have gestational diabetes, it’s good to find out early. Your doctor can then help you create a diet and exercise program that will keep the problem in check and safeguard the health of your baby. He may also prescribe insulin if necessary. Finding out that you have diabetes is certainly upsetting, but it’s not cause for great alarm. Most women who develop diabetes during pregnancy go on to have normal, healthy babies. Be aware, however, that although gestational diabetes will probably disappear after the birth of the baby, some women ultimately develop full-fledged diabetes within the next 20 years. This is something you’ll have to watch out for at yearly follow—up tests.

Alpha-Fetoprotein Screening Test

Alpha-fetoprotein (AFP) is a type of protein produced only by a fetus—you do not produce it on your own. Sometime between Weeks 16 and 18, your doctor will take a blood sample from you to check the level of this protein, which can give an indication of the risk of certain birth defects. A high level of AFP might mean trouble; a low level might mean another kind of trouble.

High levels of AFP indicate the possibility of various things: It could mean twins, or that you have been pregnant longer than you thought. It could also mean that the baby has a neural tube defect, such as spina bifida (a deformity of the spinal column) or anencephaly (the absence of all or part of the brain).

Low levels of AFP mean you might be earlier in your pregnancy than you thought, or it can mean that the baby has a birth defect called Down’s syndrome.

The AFP test is just like any other blood test and it is not risky at all—it will not hurt or harm you or your baby. The real risk associated with this test is the same one you’ll find with all screening tests—the results are not absolute and can cause a lot of needless worry. If your test results are low, for example, there is a very, very slim (some say minute) chance that your baby may have Down’s syndrome. To find out for sure, you will need to have further diagnostic testing done, such as amniocentesis. This test is a bit risky and has been known to cause miscarriages in a percentage of cases. A low or high result on an AFP test can put the fear of birth defects in your heart. The risks involved in taking the diagnostic tests add to the fear of miscarriage, as well. If the results come back either too high or too low, deciding what to do next is the most difficult part of the AFP test. The decision is ultimately what to do with a defective fetus. Do you abort it or do you want to know early on what the challenges are that you’ll be facing at birth? There are other choices, such as adoption for Down’s syndrome infants. Parents need to think, before they take an AFP, what they’ll do with the results. You may be advised to take the screening test again, seek a second opinion, and/or meet with a genetic counselor. Whatever your choice, you must always keep in mind that most women who get abnormal screening test results give birth to normal babies.