Integrated first- and second-trimester Down syndrome screening test among unaffected IVF pregnancies

Abstract

Objective: The aim of the current study was to assess the profile of markers that constitute the integrated test and to measure its false-positive rates (FPR) among a preselected group of unaffected IVF pregnancies. These results were compared with the reference laboratory values that reflect the general obstetric population, which underwent the same investigative protocol.

Methods: Ninety-nine unaffected singletons from IVF-pregnant women and 1781 controls, all evaluated by the same laboratory, underwent a nondisclosure integrated Down syndrome screening test. This test comprised first-trimester nuchal translucency (NT) and pregnancy-associated plasma protein-A (PAPP-A) assessment, followed by a midgestation quadruple test. Only upon completion of the integrated screening test, the parturient women were informed of its results.

Results: The mean maternal age of the study and the control group was 32.2 +/- 4 and 30.4 +/- 4 years respectively (t-test <0.005). The marker levels were expressed as multiples of the gestation-specific normal medians. The IVF group had lower PAPP-A (0.78 vs 1.03, t-test P < 0.05) and higher NT (1.14 vs 1.01, t-test P < 0.05) values, respectively. All the other markers were similar for both groups. On the basis of the integrated test, a higher rate of IVF pregnancies were defined as being screen-positive (6.1% vs 3.7%), although the values did not reach a level of statistical significance.

Conclusions: Since NT alone yielded the same FPR as the integrated test, the option of various sonographic screening combinations in this group warrants further investigation.