Prenatal screening for aneuploidies and adverse pregnancy outcome : the significance of second trimester soft markers and low first trimester PAPP-A

Soft markers (SMs) were introduced into second trimester ultrasound (US) screening for Down syndrome (DS) in the 1980s. It was noticed, that these minor anatomic variations were more common in fetuses with DS. Since the 1990s, the primary screening method for DS has been the combined first trimester screening (FTS). It is effective and constitutes of the measurement of fetal nuchal translucency (NT), maternal serum pregnancy-associated plasma protein A (PAPP-A) and free beeta subunit of human chorionic gonadotropin (hCG). Thereafter, the value of second trimester SMs in screening for DS has been questioned, but some of them [short fetal femur (SF) and humerus (SH)] have shown potential as markers of adverse pregnancy outcome. As a placenta derived protein, also PAPP-A has been studied as an independent marker of adverse pregnancy outcomes, i.e. preterm delivery (PTD), pre-eclampsia (PE), a small for gestational age newborn (SGA), spontaneous abortion (SA) and stillbirth (SB). The aim of the study was to assess the significance of SMs in screening for DS after normal FTS, and to evaluate the significance of isolated second trimester SF (