Prenatal Tests

These are medical tests done to determine the health of mother and baby during pregnancy. These are just a few of the most common tests but there are many others for a variety of maternal and fetal conditions that may be recommended.

Alpha-fetoprotein test (AFP)

This blood test is usually part of “the triple test” that measures three substances in a pregnant woman’s bloodstream between 16 and 18 weeks. High AFP levels may indicate a neural tube defect. This test can also detect a high risk for Down syndrome.

Amniocentesis

A small amount of amniotic fluid is withdrawn and tested for chromosomal and biochemical problems (typically done at 16 to 18 weeks, when there are enough cells in the fluid to test). Both this screener and the CVS (below) pose some risk of miscarriage since they are invasive.

Cell-free fetal DNA testing

This blood test became available in the US in 2011, is also called noninvasive prenatal screening or testing. The baby’s DNA to see if he has certain genetic conditions early in the first trimester.

Chorionic villus sampling (CVS)

Samples of the villi (hair-like projections) on placental tissue (chorion) are tested for chromosomal abnormalities. This test can be performed as early as nine weeks.

Ultrasound

This technique (also known as sonogram) of high-frequency sound waves is used to confirm other tests by creating a visual image of the uterus and the developing embryo or fetus. Ultrasound can be used throughout pregnancy to “see” the developing baby and assess his or her development. Newer techniques such as nuchal translucency can identify chromosomal conditions as early as 11-13 weeks of pregnancy.