Table 3.

Regression analysis of motor development milestones and head circumference by handedness and birthweight

					Model 1		Model 2		Model 3
	Left-handers		Right-handers		Handedness		Birthweight		Handedness		Birthweight
Sample/measure	M, SD	N	M, SD	N	Beta	P	Beta	P	Beta	P	Beta	P
Japan
Motor development*	0.57 (2.02)	47	−0.14 (1.72)	339	0.71	0.049	−2.11	<0.001	0.28	0.270	−2.10	<0.001
Head circumference	29.3 (2.23)	60	30.13 (2.39)	496	−0.83	0.012	4.57	<0.001	−0.01	0.978	4.54	<0.001
The Netherlands
Motor development*	0.12 (1.82)	9	0.004 (1.89)	56	0.27	0.715	−1.01	0.032	0.13	0.833	−0.85	0.085

^*First unrotated component of the five motor development milestones (turning, sitting, crawling, standing alone, walking alone). Higher values indicate more delayed motor development. All models included sex as a covariate. Models 1 and 2 had only one covariate of importance, handedness, and birthweight, respectively. Model 3 included both independent variables.