Table 2.

Age in Months of Milestone Achievement by SCT¹

	XXY (N=174)	XYY (N=50)	XXX (N=74)	Overall Kruskal-Wallis P-Value
Language
Cooing	N = 165	N = 46	N = 68
Median [IQR]	2 [1.5, 3]	2.8 [2, 5]	2.5 [2, 4]	0.005* 1, 2
Babbling	N = 158	N = 44	N = 61
Median [IQR]	7 [6, 9]	7.2 [5.9, 9]	7 [5, 9]	0.867
First Words	N = 152	N = 36	N = 55
Median [IQR]	12 [11, 14]	12 [11, 14]	12 [10.5, 12.5]	0.557
2 Word Phrases	N = 135	N = 23	N = 42
Median [IQR]	23 [18, 24]	23 [19, 30]	22.5 [18, 24]	0.637
Motor
Rolling Front to Back	N = 162	N = 44	N = 64
Median [IQR]	4.5 [3.5, 5.5]	4 [4, 5.6]	4.5 [3.8, 5]	0.891
Rolling Back to Front	N = 162	N = 43	N = 64
Median [IQR]	5 [4, 6]	5 [4, 7]	5 [4.4, 6]	0.193
Sitting	N = 164	N = 45	N = 60
Median [IQR]	6 [5.4, 7]	6 [6, 7]	6 [5.5, 7]	0.354
Crawling	N = 162	N = 44	N = 62
Median [IQR]	8 [7, 9.9]	9 [7.9, 10]	9 [8, 10]	0.050*2
Cruising	N = 157	N = 41	N = 62
Median [IQR]	10 [9, 11]	11 [10, 12]	11 [10, 12]	0.012*2
Walking	N = 156	N = 32	N = 53
Median [IQR]	13 [12, 15]	14 [12, 15]	14 [12, 16]	0.239
Running	N = 145	N = 27	N = 51
Median [IQR]	18 [15, 20]	18 [16, 20]	18 [17, 20.5]	0.177
Jumping	N = 131	N = 22	N = 43
Median [IQR]	23 [20, 30]	26.2 [22, 31.5]	23 [21.5, 29]	0.374

^*Significant difference in at least one trisomy; alpha = 0.05

¹Pairwise test XXY ≠ XYY; Bonferroni adjusted alpha = 0.017

²Pairwise test XXY ≠ XXX; Bonferroni adjusted alpha = 0.017