. 2019 Aug 8;14(8):e0220979. doi: 10.1371/journal.pone.0220979

Table 2. Sample characteristics and demographic breakdown for twins and triplets.

	Twins (n = 23,986)	Triplets (n = 709)
Positive or negative result	93.95% (22,536)	78.70% (558)
Total non-reportable (QNS + Technical)	6.05% (1,450)	21.30% (151)
QNS (low fetal fraction)	5.47% (1,313)	20.60% (146)
Technical non-reportable	0.57% (137)	0.71% (5)
Mean maternal age	35.0 years (range 14.5 years– 61.5 years)	35.0 years (range 18.3 years– 49 years)
Mean gestational age^a	13 weeks 5 days (range 9 weeks– 38 weeks)	13 weeks 1 day (range 9 weeks– 33 weeks)
Mean maternal BMI^b	27.64 kg/m²	27.59 kg/m²
Average fetal fraction	12.33%	13.20%

^aGestational age was determined by LMP or ultrasound as provided on the TRF.

^bMaternal height and weight are not required for testing and thus not provided for all samples