Table II.

Predictors of skeletal maturity at age 9 years in 467 white children in the Fels Longitudinal Study and 196 South African black children in the Birth to Twenty: parameter estimates (standard errors) from multivariate linear regression models

	Model 1				Model 2				Model 3				Model 4
Variable	Fels	P	Bt20	P	Fels	P	Bt20	P	Fels	P	Bt20	P	Fels	P	Bt20	P
Sex (female)	0.16 (0.10)	.10	0.34 (0.12)	.005	0.23 (0.10)	.022	0.45 (0.12)	<.0001	0.20 (0.10)	.037	0.40 (0.12)	.001	0.13 (0.09)	.137	0.38 (0.11)	.001
Gestational age (weeks)	0.04 (0.04)	.24	−0.02 (0.04)	.706	0.01 (0.04)	.70	−0.08 (0.04)	.066	0.05 (0.04)	.18	−0.08 (0.04)	.056	0.04 (0.03)	.236	−0.07 (0.04)	.071
Birth year (year)	0.01 (0.003	.025	-	-	0.01 (0.003)	.014	-	-	0.002 (0.003)	.34	-	-	0.001 (0.002)	.593	-	-
Weight gain 0-2 (SDS change)	0.21 (0.05)	<.0001	0.16 (0.06)	.004	0.29 (0.05)	<.0001	0.28 (0.06)	<.0001	0.18 (0.05)	.005	0.20 (0.07)	.003	−0.14 (0.06)	.014	0.04 (0.07)	.567
Birth weight (SDS)	-	-	-	-	0.18 (0.07)	.006	0.32 (0.08)	<.0001	0.01 (0.07)	.91	0.23 (0.08)	.006	−0.28 (0.07)	<.0001	0.03 (0.09)	.712
BMI at age 9 (SDS)		-	-	-	-	-	-	-	0.38 (0.05)	<.0001	0.17 (0.06)	.007	0.33 (0.05)	<.0001	0.17 (0.06)	.005
Height at age 9 (SDS)	-	-	-	-	-	-	-	-	-	-	-	-	0.52 (0.05)	<.0001	0.33 (0.06)	<.0001
Adjusted R2	0.043		0.077		0.057		0.149		0.161		0.177		0.316		0.285

Model 1 adjusts for sex, gestational age, maternal age, parity, birth year (FLS only), and weight gain 0 to 2 years.

Model 2 adjusts for sex, gestational age, maternal age, parity, birth year (FLS only), weight gain 0 to 2 years, and birth weight.

Model 3 adjusts for sex, gestational age, maternal age, parity, birth year (FLS only), weight gain 0 to 2 years, birth weight, and BMI at age 9 years.

Model 4 adjusts for sex, gestational age, maternal age, parity, birth year (FLS only), weight gain 0 to 2 years, birth weight, BMI at age 9, and height at year 9.