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This collection is comprised of peer-reviewed educational articles selected by the editor and provides a wealth of information around noninvasive prenatal testing from well-respected titles in obstetrics, gynaecology and genetics.

Population‐based trends in the prenatal diagnosis of sex chromosome aneuploidy before and after non‐invasive prenatal testing

Objective
To assess the impact of non‐invasive prenatal testing (NIPT) on trends in the prenatal diagnosis of sex chromosome aneuploidy (SCA) in a population with >73,000 annual births.

Method
Retrospective population‐based cohort study from 1986–2016 of all women undergoing prenatal diagnosis before 25 weeks gestation in the Australian state of Victoria. Statistical significance was tested using the chi‐square test for trend or proportions.

Results
There were 2,043,345 births and 842 SCA diagnoses from 1986–2016. The percentage of prenatal diagnostic tests leading to a SCA diagnosis increased significantly from 0.95% in 2010 to 2.93% in 2016 (p < 0.001) but due to a concurrent decline in testing, the annual prenatal diagnosis rate of SCA remained stable at 4.4/10,000 births. Among confirmed fetal SCAs the most common indication for testing in 1986 was advanced maternal age (63%); in 2016 it was high risk NIPT (49%).

Conclusion
SCAs now make up an increasing proportion of prenatal diagnostic results but due to the overall decline in diagnostic testing, the prenatal prevalence as a percentage of births remained steady. The ascertainment of fetal SCA has evolved from an incidental finding after testing for increased risk of trisomy 21, to a diagnosis obtained after suspected SCA on NIPT.

This article can be viewed on Wiley Online Library.
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