Chromosomal mosaicisms in prenatal diagnosis: correlation with first trimester screening and clinical outcome

Abstract

Objective: To investigate the outcome of pregnancy after detection of chromosomal mosaicism and to determine the correlation between human chorionic gonadotropin (free β-HCG) and pregnancy-associated plasma protein-A (PAPP-A) levels from first-trimester-screening with pregnancy outcome.

Methods: In a single-center, retrospective survey of the results of prenatal diagnostics performed between January 2000 and March 2011, we identified a total of 40 pregnancies with chromosomal mosaicism. Clinical characteristics and results of first-trimester screening, as well as the outcome of these cases, are described.

Results: Out of 40 cases, 21 were defined as confined placental mosaicism, 10 classified as true mosaicism and nine were not classifiable cases. Nuchal translucency (NT) was ≥2.5 mm in 8/30 cases with respective measurements. PAPP-A levels were ≤0.4 MoM in 9/26 cases, with respective measurements, two of them being newborns with growth restriction. Remarkably, in pregnancies of all four children born with severe growth retardation, <3rd percentile PAPP-A levels were below 0.52 MoM.

Conclusions: Our observations show mosaic pregnancy outcomes to be very heterogeneous. Nevertheless, a combination of low PAPP-A and interpretation of chromosomal mosaicism might identify pregnancies at particular risk for fetal growth restriction.