Additive effect of factors related to assisted conception on the reduction of maternal serum pregnancy-associated plasmaprotein A concentrations and the increased false-positive rates in first-trimester Down syndrome screening

Objective: To analyze whether assisted conceptions need adjustments in first-trimester Down syndrome screening and why modifications in screening markers occur. Design: Eleven-year cohort retrospective analysis. Setting: Maternal-fetal medicine unit. Patient(s): Two thousand eleven naturally conceived normal singleton pregnancies and 2,042 normal singleton pregnancies achieved with assisted conception: 350 by IUI and 1,692 with IVF (n = 328) or intracytoplasmic sperm injection (ICSI; n = 1,364), using nondonor (n = 1,086) or donated ova (n = 606), with fresh (n = 1,432) or frozen (n = 260) embryos. Intervention(s): Comparison of ultrasound and biochemical markers of first-trimester Down syndrome screening according to the mode of conception and considering the clinical and laboratory parameters related. Main Outcome Measure(s): Nuchal translucency (NT), PAPP-A and free beta hCG maternal serum concentrations, and false-positive rates (FPRs). Result(s): NT is unaffected by the mode of conception. Singleton pregnancies achieved by IVF and ICSI with nondonor oocytes have reduced maternal serum PAPP-A and increased FPR, which are significant only in ICSI cycles. Pregnancies from frozen embryos with hormone therapy also show decreased PAPP-A but without affecting the FPR. Elevated maternal serum f beta hCG levels in oocyte donation do not influence the FPR. Conclusion(s): Among assisted conceptions, only nondonor IVF/ICSI singleton pregnancies need adjustments of the maternal serum PAPP-A in first-trimester Down syndrome screening. (C) 2013 by American Society for Reproductive Medicine.