Positive predictive value of non-invasive prenatal screening for fetal chromosome disorders using cell-free DNA in maternal serum: independent clinical experience of a tertiary referral center

Table 1 Maternal age at delivery and gestational age at time of NIPS, stratified by NIPS results

			Median	Mean	SD	P-values^a
Maternal age (years)	I.	Abnormal concordant	39.00	36.97	6.13	I vs. III	0.009**
	II.	Abnormal discordant	34.00	33.08	4.70	I vs. II	0.034*
	III.	Normal concordant	36.00	34.79	5.16	II vs. III	0.161
Gestational age (weeks)	I.	Abnormal concordant	13.10	14.94	3.74	I vs. III	0.156
	II.	Abnormal discordant	14.10	15.76	4.17	I vs. II	0.722
	III.	Normal concordant	13.25	15.64	3.97	II vs. III	0.627

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