Breakdown of Prenatal Testing

You've probably heard the stories from women older than yourself-about how they didn't know they were having twins until they delivered them. Or how they labored for hours with a baby that never dreamed of coming out because they were breech or had another presentation problem. Many years ago, these problems could have been deadly for mothers, their babies, or both. But thankfully, the technology surrounding the birth of your next baby will help ensure that your delivery goes much more smoothly than it did even a decade or two ago. But with so much technology comes even more questions-is so much prenatal testing necessary?

While some tests are optional, there are others that are more than just suggested-they are absolutely essential. Not every woman will need to have every type of test, so remember that if your doctor doesn't mention having all of these, that's fine. If you are interested in one particular test, make sure to ask your doctor about it.

1st Trimester Tests

Most health care providers have a relatively similar set of blood work that they will need to collect on your first visit. He or she will determine when you had your last Pap smear and if needed, they will probably complete the test that day or may schedule you to come back in to complete it. A pap smear is a test that looks for abnormal cells of the cervix that could lead to cervical cancer. You will probably be screened for sexually transmitted diseases at the same time with a simple swab that is sent off for testing.

You may also be prepared for an ultrasound to confirm that your baby is growing as it should be. This will be a vaginal ultrasound-no belly scans yet because your baby is still much too small. Instead a lubricated wand will be inserted into the vagina to see what stage of development your baby is in. Don't be alarmed if you don't see anything on your first visit-if you are earlier than 6 or 7 weeks (even if you think you are further along) you may not see anything, and that can be normal, though it certainly rattles the nerves of many couples.

After you are done in the office, be ready to roll up your sleeve for blood work. Among the tests that will usually be completed will be a blood type, Hepatitis, Rubella, and Syphilis result. Each of these components can dramatically affect the health of your baby if they are present and go untreated, so don't think you can skip out on them.

2nd Trimester Tests

Around weeks 15 to 18, but no later than week 20, you will be offered the traditional "triple screen" test. The "triple screen" detects three key components: the alpha fetoprotein (AFP or MSAFP), hCG, and estriol in the blood in an attempt to identify babies who are at risk for being born with a chromosomal abnormality like Down's syndrome, Trisomy-18, or neural tube defects like Spina Bifida. This test has a high false-positive rate that has been hotly debated. Some research estimates that it provides a false positive rate as much as 80% of the time. This test is completely optional, and many parents choose to opt out of it completely unless there is a family history or other factor that might raise the risk.

If you should decide to have a triple screen test, and you do get a positive result, your doctor will probably repeat the blood work, and do an in-depth ultrasound. After that, he or she may talk with you about an amniocentesis or chorionic villus sampling (CVS).

CVS testing is usually conducted during the first trimester, around the 10th to 12th week, where amniocentesis testing doesn't occur until 15-20 weeks. Chorionic villi are a component of the placenta, and have been shown to have the same information contained there as the baby's cells. The information that can be collected from CVS has been easier to collect, demonstrates consistent reliability and gives parents an accurate picture of whether or not their baby has a genetic or chromosomal disorder. By testing earlier than with an amniocentesis, parents may have more time to decide whether or not to terminate the pregnancy.

3rd Trimester Tests

Weeks of considering, testing and thinking have led up to your final days of pregnancy-but we aren't done yet.

The glucose tolerance test (GTT) will be conducted somewhere between your 24th and 28th week of pregnancy. The GTT looks at how your body tolerates and utilizes blood sugar. It is common during pregnancy for hormones to make it difficult for the body to properly utilize insulin-which puts some mothers at risk for gestational diabetes. The GTT requires you to drink a sugary liquid and wait one hour to have your blood drawn. These results are sent to your doctor and if they are too high, you will need to complete your three hour GTT. Some facilities will test only by sticking your finger; others will draw blood on the hour for three hours and then test the glucose level. If your levels are too high, you will be labeled as a gestational diabetic and will need to follow your doctor's orders to keep your sugar under control.

Between weeks 34 and 37, you will be tested in the office for group B strep (GBS) by collecting a vaginal and rectal swab sample. GBS is a common bacterium that lines the digestive and vaginal tracts of up to 30% of women. Typically causing no problems, GBS can infect your baby-- causing blindness, hearing loss, and deadly infections after birth. If you do test positive, your doctor will treat you with antibiotics during labor to prevent spreading GBS to the baby. If you are not treated, or are unable to complete the antibiotics before delivery, your baby may need to have additional blood work and cultures after birth to help ensure that they are not infected.

As you near your due date, you may be asked by your doctor to take a Nonstress test (NST) or to have a Biophysical Profile (BPP). These exams study your baby's heart rate in relation to its movement through the use of a fetal monitoring device. The Biophysical Profile also uses ultrasound to analyze breathing movements, fluid levels and other components to determine how well your baby is growing and developing in utero. These tests may be more common in women who have risk factors like gestational diabetes, a baby with a genetic or birth defect, or for moms who have carried past their due date.