Table II.

Sociodemographic characteristics of the cohorts

Characteristica	Children born 1993–1994 (exploratory cohort)			Children born 1995–2000 (confirmatory cohort)			pb
	n	%	95% CI	n	%	(95% CI)
Overall	1080	100		4022	100
Mother’s age
≤19y	193	18	16–20	695	17	16–18	0.7
20 y+	887	82	80–84	3324	83	82–84
Primary caregiver at 18–22mo
Mother	971	90	88–92	3695	92	91–93	0.04
Other female	109	10	8–12	327	8	7–9
Caregiver’s education
<12y	302	28	25–31	981	24	23–26	0.02
High-school degree+	778	72	69–75	3036	76	74–77
Total income in child’s household
<US$20 000	574	56	53–59	1659	44	42–45	<0.001
US$20 000 +	444	44	41–47	2129	56	55–58
Child’s medical insurance
Medicaid	674	63	60–65	2354	59	57–60	<0.001
Private	360	33	31–36	1552	39	37–40
None	42	4	3–5	102	3	2–3

^aInformation was missing for mother’s age (n=3), caregiver’s education (n=5), household income (n=296), and child’s medical insurance (n=18).

^bp values for comparisons between the groups by Fisher’s exact or χ² test. CI, confidence intervals.