Table 2.

Comparisons of HC, weight, and height across groups from birth to the age of 24 months in 3-month intervals

Head circumference
Age	Autism	Control	Autism-control	t value	p value
Birth	34.4	35	−0.6	−2.1	0.04*
3 months	39.7	40.2	−0.5	−2.8	0.006*
6 months	42.8	43.2	−0.4	−1.7	0.1
9 months	44.7	44.9	−0.2	−1.3	0.19
12 months	45.9	46.2	−0.3	−1.3	0.21
15 months	46.7	47.1	−0.4	−1.7	0.1
18 months	47.2	47.7	−0.5	−1.9	0.06
21 months	47.7	48.3	−0.6	−1.4	0.17
24 months	48.1	49.1	−1	−1.8	0.12
Weight
Age	Autism	Control	Autism-control	t value	p value
Birth	3.2	3.4	−0.2	−2.7	0.007*
3 months	5.6	6.1	−0.5	−3.8	0.0004*
6 months	7.6	7.9	−0.3	−1.9	0.06
9 months	8.7	9	−0.3	−1.4	0.1
12 months	9.7	9.9	−0.2	−1.2	0.24
15 months	10.4	10.6	−0.2	−0.9	0.36
18 months	11.1	11.3	−0.2	−1	0.31
21 months	11.7	12	−0.3	−1.1	0.28
24 months	12.3	12.5	−0.2	−1	0.31
Height
Age	Autism	Control	Autism-control	t value	p value
3 months	59.4	60	−0.6	−1.9	0.06
6 months	66.9	67.3	−0.4	−1.2	0.24
9 months	71.5	71.8	−0.3	−1.4	0.58
12 months	75.5	75.3	0.2	−1.2	0.73
15 months	78.8	78.5	0.3	−0.9	0.53
18 months	81.7	81.5	0.2	−1	0.72
21 months	84.5	84.2	0.3	−1.1	0.63
24 months	87	86.7	0.3	−1	0.67

HC and height are in centimeters and weight is in kilograms. Columns: mean of the autism group, mean of the control group, the difference between autism and control groups, t values, and p values from a two-tailed two-sample t test with unequal variance. p values are not corrected to increase sensitivity

Asterisks: p value < 0.05