Table 1.

Baseline characteristics of patients included in statistical analysis (n = 2,366). Two triploid events were included in the trisomy category, with one triploid event the NIPS pass and one in the NIPS fail sub cohorts. Percentage of trisomy was calculated from a total of 71 as unknowns were excluded.

		NIPS results
	Total	Fail	Pass
	(n = 2,366)	(n = 103)	(n = 2,263)
Fetal fraction
Mean	9.4	2.8	9.7
SD	4.3	0.8	4.2
Median	8.8	2.9	9.0
Q1 – Q3	6.6 – 11.6	2.3 – 3.3	6.9 – 11.8
BMI
Mean	27.4	34.3	27.1
SD	6.6	7.6	6.3
Median	25.9	34.3	25.7
Q1 – Q3	22.5 – 31	30.1 – 39.4	22.3 – 30.5
Gestational age (weeks)
Mean	13.7	13.1	13.7
SD	4.34	3.11	4.4
Median	12.1	12.9	12.1
Q1 – Q3	11.0 – 14.4	11.8 – 14.1	11 – 14.4
Presence of trisomy
Yes (%)	33	2 (2.8)	31 (1.4)
No (%)	2,296	69 (97.2)	2,227 (98.6)
Unknown (%)	37	32	5
Fetal sex
Male (%)	1,207	53 (51.5)	1,154 (51.7)
Female (%)	1,129	50 (48.5)	1,079 (48.3)
Unknown (%)	30	0	30
Maternal age (years)
Mean	32.3	32.9	32.3
SD	5.2	5.2	5.2
Median	33	34	33
Q1 – Q3	29 – 36	30 – 37	29 – 36