Table 1. Summary of all samples with a Z-score > 3 for chromosomes 13, 18 or 21 in 209 samples on which NIPT was performed.

Sample	First trimester combined test risk for Trisomy 21	Coefficient of variation #21	Z-score #21	Posterior Risk (%)	Confirmation by karyotyping in amniotic fluid
1	1/4	0.40	13.7	99.9	47#, +21
2	1/2	0.29	27.2	99.9	47#, +21
3	1/79	0.31	12.4	99.9	47#, +21
4	1/118	0.40	11.6	99.9	47#, +21
5	1/141	0.33	14.4	99.9	47#, +21
6	1/119	0.47	11.9	99.9	47#, +21
7	1/13	0.32	19.7	99.9	47#, +21
8	1/20	0.36	16.9	99.9	47#, +21
9	1/115	0.29	26.2	99.9	47#, +21
10	1/25	0.33	28.8	99.0	47#, +21
11	1/43	0.33	4.9	40.0	Mos 46#/47#, +21 also seen in chorionic villi
12	1/147	0.34	4.4	36.0	46#, no T21
13	1/80	0.32	4.2	33.0	46#, no T21
*14	#13 1:5000	#13 0.18	#13 4.4	4.0	No confirmation done, healthy baby born

^*A Z-score of 4.4 for chromosome 13 was detected, while the a priori risk for trisomy 21 was 1/121; no elevated risk was found for trisomy 13 after the first trimester combined test.