Blood tests and fetal ultrasound tests for pregnant women check the levels of protein and hormones being produced by the fetus and examine how the fetus is forming. The levels of four different substances as well as early findings on ultrasound can enable doctors to identify pregnancies that are at a higher risk for birth defects such as Down syndrome or neural tube defects (brain and spinal cord problems). If the screening tests suggest problems, your doctor might recommend additional tests, such as amniocentesis or chorionic villus sampling, to confirm the findings.
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