YOU SHOULD KNOW

Valuable HPV Information

The March 20, 2006 issue of Time magazine contains extensive, valuable information about HPV.

First Trimester Screening

What is First Trimester Screening? First Trimester Screening is a way to estimate the chance that a developing baby has Down syndrome or trisomy 18, by using ultrasound to measure the skin fold on the back of the baby’s neck (nuchal translucency), and combining this with the results of the mother’s blood test. Because this two-part test is done at around 10 to 13 weeks of pregnancy (the first trimester), it is called “First Trimester Screening.”

What can First Trimester Screening tell me about my developing baby? It can tell you whether you are at higher risk for having a baby with either Down syndrome or trisomy 18. In general, one in about 20 to 25 women will have a “screen positive” First Trimester Screening test. If your test result is positive, it does not mean for sure that your baby has one of these conditions, but it does mean that you should talk with your doctor about further testing.

If my First Trimester Screening result is negative, does that mean the baby will be normal? A normal or “screen negative,” result means that the chance of your baby having Down syndrome or trisomy 18 is low enough that further testing is not needed. It is never possible to be absolutely sure that your baby is going to be normal. First Trimester Screening will help find about five out of every six babies with Down syndrome, and four out of five babies with trisomy 18. The test is not expected to find most other conditions. Even if your First Trimester Screening is normal, you may be asked to think about having other testing in the second trimester.

What are the tests that will be offered if my First Trimester Screening result is positive? In some cases, chorinic villus sampling (CVS) will be suggested. CVS is a way to take a tiny sample of tissue from the placenta. Placental cells have the same genetic information as the baby’s cells, so they can be used to tell whether the developing baby has Down syndrome or trisomy 18. In other cases, you might choose to have amniocentesis.

What is Down syndrome? Down syndrome, also called trisomy 21, is a condition that causes mental retardation and serious heart problems. One baby out of every 600 could be born with Down syndrome. Although Down syndrome occurs more often to women who are older, it can happen at any age. For more information about Down syndrome, ask your doctor.

What is trisomy 18? Trisomy 18 is caused by an extra chromosome in the developing baby. Few babies with trisomy 18 survive to birth. One in 6,000 babies could be born with trisomy 18, which causes mental retardation, heart defects, very poor growth, and other problems. For more information about trisomy 18, ask your doctor.

Why should I want to have First Trimester Screening instead of the usual second trimester screening? There are advantages and disadvantages to having First Trimester Screening. One advantage is that you will have some information about your developing baby’s health earlier in the pregnancy. While First Trimester Screening can test for Down syndrome and trisomy 18, second trimester screening can test for Down syndrome, trisomy 18, neural tube defects, and other important conditions. If you choose First Trimester Screening, some second trimester screening might also be helpful. Which tests you choose, or whether you choose any tests at all, is up to you.

For the Woman Who Will Be 35 or Older at Delivery...

Women of any age can deliver a baby with a chromosome disorder, such as Down syndrome. Women who will be 35 or older at delivery have a higher chance of having a baby with a chromosome problem. In the past, all women in this age group have been offered CVS or amniocentesis, which can detect chromosome differences 100 percent of the time.

It is also important to note that First Trimester Screening is not a diagnostic test. It cannot diagnose or rule out any specific condition; it is only used to estimate risk. First Trimester Screening does not estimate risk of chromosome abnormalities other than Down syndrome and trisomy 18, and cannot detect a majority of birth defects.

Therefore, we suggest that you discuss these issues with your doctor or genetic counselor to help you decide if this test will meet your needs.

Please remember...

Even if your First Trimester Screening test results are positive, this only means that you should think about having further diagnostic testing. It is most likely that your baby is fine.