Do I need special tests?

Depending on the circumstances, your health care provider might recommend:

• Specialized or targeted ultrasound. This type of fetal ultrasound — an imaging technique that uses high-frequency sound waves to produce images of a baby in the uterus — targets a suspected problem, such as abnormal development.
• Prenatal cell-free DNA (cfDNA) screening. During this procedure, DNA from the mother and fetus is extracted from a maternal blood sample and the fetal DNA is screened for the increased chance of specific chromosome problems.
• Invasive genetic screening. Your health care provider might recommend amniocentesis or chorionic villus sampling (CVS). During amniocentesis, a sample of the fluid that surrounds and protects a baby during pregnancy (amniotic fluid) is withdrawn from the uterus. Typically done after week 15 of pregnancy, amniocentesis can identify certain genetic conditions as well as serious abnormalities of the brain or spinal cord (neural tube defects). During CVS, a sample of cells is removed from the placenta. Typically done between weeks 10 and 12 of pregnancy, CVS can identify certain genetic conditions.
• Ultrasound for cervical length. Your health care provider might use an ultrasound to measure the length of your cervix at prenatal appointments to determine if you're at risk of preterm labor.
• Lab tests. Your health care provider will test your urine for urinary tract infections and screen you for infectious diseases such as HIV and syphilis.
• Biophysical profile. This prenatal ultrasound is used to check on a baby's well-being. It might involve only an ultrasound to evaluate fetal well-being or, depending on the results of the ultrasound, also fetal heart rate monitoring (nonstress test).

Some prenatal diagnostic tests — such as amniocentesis and chorionic villus sampling — carry a small risk of pregnancy loss. The decision to pursue these tests is up to you and your partner. Discuss the risks and benefits with your health care provider.