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

Among assisted conceptions, only nondonor in vitro fertilization/intracytoplasmic sperm injection singleton pregnancies need adjustments of the PAPP-A in first-trimester Down syndrome screening.


José Bellver, M.D., Cristina Casanova, M.D., Nicolás Garrido, Ph.D., Coral Lara, M.D., José Remohí, M.D., Antonio Pellicer, M.D., Vicente Serra, M.D.

Volume 100, Issue 5, Pages 1314-1320.e3, November 2013



To analyze whether assisted conceptions need adjustments in first-trimester Down syndrome screening and why modifications in screening markers occur.


Eleven-year cohort retrospective analysis.


Maternal-fetal medicine unit.


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.


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 βhCG maternal serum concentrations, and false-positive rates (FPRs).


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 fβhCG levels in oocyte donation do not influence the FPR.


Among assisted conceptions, only nondonor IVF/ICSI singleton pregnancies need adjustments of the maternal serum PAPP-A in first-trimester Down syndrome screening.

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