Validation of correction factors for serum markers for first-trimester Down syndrome screening in singleton pregnancies conceived with assisted reproduction.

OBJECTIVE To validate previously computed correction factors for free β-human chorionic gonadotrophin (fβ-hCG) and pregnancy-associated plasma protein-A (PAPP-A) in in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) pregnancies with hormone treatment and to determine the effect on false-positive rate (FPR). METHODS Retrospective study on 249 IVF and 250 ICSI cases and 20,190 controls. Correction factors 1.42 (PAPP-A), 1.17 (fβ-hCG) in IVF; 1.56 (PAPP-A) in ICSI were applied on the absolute serum concentrations. Analysis was done on log10-transformed multiples of medians (MoMs). RESULTS In the controls, mean PAPP-A and fβ-hCG MoM were 1.004 and 1.062. Before correction, mean PAPP-A MoM was significantly lower in IVF (0.757; p < 0.001) and in ICSI (0.671; p < 0.001) and after correction comparable (1.071; p = 0.053 in IVF; 1.048; p = 0.178 in ICSI). Before correction, mean fβ-hCG MoM was comparable (1.054; p = 0.59 in IVF and 1.051; p = 0.56 in ICSI) and after correction significantly higher in IVF (1.241; p < 0.001). After correction the likelihood for receiving a false-positive result was 1.03 in IVF pregnancies (95% CI 0.98-1.09; p = 0.248) and 1.02 in ICSI pregnancies (95% CI 0.97-1.07; p = 0.448). CONCLUSIONS After correction the FPR in IVF and ICSI pregnancies with hormone treatment reduces to the observed FPR in the controls.