Individual tests

Second-trimester prenatal screening includes several blood tests that assess the risk of having a baby with certain genetic conditions or birth defects. Screening is usually done between the 14th and 22nd weeks of pregnancy (the 16th to 18th is ideal). A triple test includes AFP, hCG, and Estriol. Any abnormal result requires more testing. Usually, an ultrasound, or even an amniocentesis, may be needed for an accurate diagnosis.