Pregnancy is a time of great anticipation and lots of decisions. While most babies are born healthy, you may worry that your baby will have health problems. Doctors can diagnose many genetic abnormalities before birth. And you can get important genetic information even before getting pregnant. Your health care provider may recommend genetic testing during pregnancy if you or your partner has a family history of genetic disorders.
Different Kinds Of Tests
The two main types of prenatal testing are:
Screening tests. Prenatal screening tests are usually offered during the first or second trimester. These tests identify whether your baby is more or less likely to have certain congenital disabilities, many of which are genetic disorders. Screening tests aren’t a definitive diagnosis. If results indicate an increased risk for a genetic disorder, your health care provider will discuss your options for a diagnostic test.
Diagnostic tests. Suppose a screening test indicates a possible problem or your age, family history, or medical history puts you at increased risk. In that case, your health care provider may recommend a diagnostic test to confirm a diagnosis. Some diagnostic tests, such as chorionic villus sampling and amniocentesis, carry a slight risk of miscarriage.
When Are Screening Tests Scheduled?
Pre-Pregnancy Screening Tests
You are a carrier if you have a gene for a disorder but don’t have the condition yourself. Genetic carrier screening tells you if you or your partner have these genes and, if so, the chances you’ll pass them on to your children. You can get the tests before or during pregnancy, but they’re most useful beforehand.
Some ethnic groups are more likely to be carriers for some conditions, so ask your health care provider if you’re in a high-risk category.
First Trimester Screening Tests
During your first trimester, your health care provider will offer a blood test and an ultrasound to measure the size of the clear space in the tissue at the back of a baby’s neck (nuchal translucency). The nuchal translucency measurement is abnormally large in Down syndrome and certain other conditions.
Second Trimester Screening Tests
During your second trimester, your health care provider will offer another blood test called the quad screen. This test measures levels of four substances in your blood. Results indicate your risk of carrying a baby with certain chromosomal conditions, such as Down syndrome. The test can also help detect neural tube defects — serious brain or spinal cord abnormalities.
Although not a comprehensive list, these are some of the genetic disorders that obstetricians can diagnose before birth:
- Cystic fibrosis
- Duchenne muscular dystrophy
- Hemophilia A
- Polycystic kidney disease
- Sickle cell disease
- Tay-Sachs disease
The decision to pursue prenatal testing is optional. Discuss the risks and benefits with your health care provider if you’re concerned about prenatal testing. You might also meet with a genetic counselor for help choosing a test and understanding the results.
If you have questions or concerns about genetic testing during pregnancy, contact us to schedule an appointment at 479.582.9268.