The epidemic of abnormal copy number variant cases missed because of reliance upon noninvasive prenatal screening.

Objective: To assess the implications of increasing utilization of noninvasive prenatal screening (NIPS), which may reach 50% with the concomitant decrease in diagnostic procedures (DPs) for its impact on detection of chromosomal abnormalities.

Methods: We studied our program's statistics over 5 years for DPs and utilization of array comparative genomic hybridization (aCGH). We then modeled the implications in our program if DP had not fallen and nationally of a 50% DP and aCGH testing rate using well-vetted expectations for the diagnosis of abnormal copy number variants (CNVs).

Results: Our DP fell 40% from 2013-2017. Utilization of aCGH for DP nearly tripled. We detected 28 abnormal CNVs. If DP had not fallen, we likely would have detected 60. With 4 million US births per year, 2 million DPs would detect 30 000 abnormal CNVs and 4000 standard aneuploidies. At a 1/500 complication-pregnancy loss rate, the detection/complication ratio is 8.5/1.

Conclusions: Noninvasive prenatal screening has significantly changed the practice of prenatal screening. However, while increasing the detection of Down syndrome, the concomitant decrease in DP and lack of aCGH results in missing many more abnormalities than the increase in Down syndrome and complications of DP combined. From a public health perspective, such represents a missed opportunity for overall health care delivery.