Table 3.

Maternal age and the ratios of 16, 22, 21, 13, and 18 trisomies and X monosomy

Maternal age	16 trisomy, n (%)	22 trisomy, n (%)	21+13+18 trisomy, n (%)	X monosomy, n (%)
<35	98 (14.6)	38 (5.6)	35 (5.2)	45 (6.7)
≥35	23 (14.5)	18 (11.3)	16 (10.1)	12 (7.5)
P	0.975	0.01*	0.027†	0.699

The rate of trisomy 16, as well as the rate of monosomy X, was similar in the advanced maternal age and young maternal age groups (P=0.975, P=0.699). The rates of trisomy 22 and the total rate of trisomies 21, 13 and 18 of the advanced maternal age group were significantly higher than those of the young maternal age group (*P=0.01, ^†P=0.027).