Normal values of three items of Tang sieve

Down's screening tests are alpha-fetoprotein, human chorionic gonadotropin, and free estriol. Normal levels for alpha-fetoprotein are 0.7 to 2.5 mom, normal levels for human chorionic gonadotropin are 0.4 to 2.5 mom, and normal levels for free estriol are about 0.7 mom. If Down's syndrome is at high risk, an amniocentesis test may be performed.