First trimester screening for Down's syndrome using maternal serum PAPP‐A and free β=hCG in combination with fetal nuchal translucency thickness

The aim of this study was to evaluate the potential effectiveness of maternal serum pregnancy‐associated plasma protein A (PAPP‐A) and free β‐hCG in combination with nuchal translucency thickness in first trimester screening for Down's syndrome. Maternal serum levels of PAPP‐A and free β‐hCG were assayed in stored sera from 32 Down's syndrome and 200 unaffected pregnancies. Fetal nuchal translucency was measured by ultrasound at the time of blood sampling. Screening of Down's syndrome using a combination of maternal age, PAPP‐A, free β‐hCG and nuchal translucency would achieve a detection rate of 75.8% for a false positive rate of 5%.