Things to keep in mind
If blood tests indicate that your baby is at increased risk for a birth defect, your doctor will perform additional tests. These tests include:
- High resolution ultrasound: This is also called a level II ultrasound. It provides more details about possible birth defects. It checks the baby’s age, brain, spinal cord, kidneys, and heart. It is usually performed between 18 and 22 weeks of pregnancy.
- Chorionic villus sampling (CVS): This is an invasive test. Your doctor will collect a small sample of the placenta, called a chorionic villus, to test for chromosomal or genetic disorders. CVS testing is offered to people who have had an abnormal result on a first-trimester screening test. It is also offered to people who might be at higher risk. It is done between weeks 10 and 12 of pregnancy.
- Amniocentesis: This is an invasive test. The doctor will remove a small amount of amniotic fluid from the area around the baby to test it for certain proteins. This can determine if the baby has Down syndrome or other genetic problems. It is recommended for women who have had an abnormal blood test during a pregnancy screening test. It is done between 15 and 18 weeks of pregnancy.
Most diagnostic tests are offered to people with higher-risk pregnancies. This includes people age 35 or older, people who have had a previous pregnancy affected by a birth defect, people who have chronic diseases such as lupus, high blood pressure, diabetes, or epilepsy, or people who take certain medications.
If your doctor discovers a birth defect during pregnancy or at the time of delivery, he or she may refer you to a genetic counselor. This is an expert who can explain test results, order additional tests, and refer you to a doctor who specializes in high-risk pregnancies or genetic diseases.
Other considerations
- Pregnancy testing is a personal choice. If the test result is abnormal (positive), do you want to take the next step? This would be a diagnostic test. Will it affect how you manage your pregnancy?
- Some screening tests give false positive results, meaning your baby may not have a birth defect. A false positive result may or may not affect your options for further testing or cause you stress. If a screening test is normal, it can give you peace of mind.
