PAPPA and Down syndrome: PAPP-A levels were only different between OS and IVF pregnancies (p < 0.05). fβhCG values in IVF and ICSI were above those found in normal pregnancies, (p = 0.02). The data collected so far show that biochemical markers of the first trimester either do not need to be adjusted because they have no effect on FPRs in ART-derived pregnancies or the effect is very small. Thus, the first trimester of integrated ultrasound and biochemical screening for Down's syndrome in assisted reproductive pregnancies seems possible. That is, it is not a false positive.