Screening for trisomies 21, 18 and 13 by maternal age, fetal nuchal translucency, fetal heart rate, free  -hCG and pregnancy-associated plasma protein-A

As a side effect of first-trimester screening for trisomy 21, approximately 95% of trisomy 13 and 18 fetuses can be detected with an 0.1% increase in the FPR.