trisomy 21 risk based on maternal age + alpha-1-fetoprotein + choriogonadotropin + unconjugated estriol in fetus
trisomy 21 risk based on maternal age + alpha-1-fetoprotein + choriogonadotropin + unconjugated estriol in fetus
trisomy 21 risk based on maternal age+AFP+choriogonadotropin+unconjugated estriol fetus
trisomy 21 risk based on maternal age+afp+choriogonadotropin+unconjugated estriol fetus