Table 1.

Analytic sample description (N = 1,567)

Variable	Mean (SD)	N	Percent
Child’s telomere length (logged)a	2.03 (0.31)
Hours of sleep – age 9a	8.97 (1.08)
Child’s age in monthsa	112.14 (4.31)
Child low birth weight (< 2,500 grams)b		140	8.9%
Child maleb		821	52.4%
Child’s puberty progressiona	1.45 (0.35)
Child’s BMIa	19.24 (4.97)
Child ever diagnosed with ADHD/ADDa		164	10.5%
Child ever diagnosed with autisma		11	0.7%
Mother’s ageb	25.03 (5.99)
Father’s ageb	27.54 (7.17)
Mother’s telomere length (logged)a	1.85 (0.30)
Mother non-Hispanic whiteb		357	22.7%
Mother non-Hispanic blackb		711	45.4%
Mother Hispanicb		444	28.3%
Mother other race/ethnicityb		55	3.5%
Mother foreign bornb		243	15.5%
Mother has less than high school educationb		487	31.1%
Mother has high school diploma or GEDb		496	31.7%
Mother attended some collegeb		397	25.3%
Mother is a college graduateb		187	11.9%
Mother’s household incomeb	$35,276.42 ($34,005.08)
Biological parents have no relationshipb		474	30.2%
Biological parents cohabitingb		648	41.4%
Biological parents marriedb		445	28.4%
Number of children in homeb	1.19 (1.25)

^aMeasured at age 9.

^bMeasured at child’s birth.