TABLE 1.

Characteristics of Mothers, Fathers, and Children in the Total Child Health and Development Study and the Subgroups Included in the Current Study^*

Characteristic	Sampling Strata†				Final Sample (n = 399)		CHDS Population (n = 20,754)
	Stratum 1 (n = 240)		Stratum 2 (n = 159)
	No.	%	No.	%	No.	%	No.	%
Maternal age (yrs)
<20	20	8	8	5	28	7	1731	8
20–29	143	60	99	63	242	61	12,028	59
≥30	77	32	51	32	128	32	6724	33
Parity
0	69	29	53	33	122	31	6289	31
1–2	106	44	71	45	177	44	9270	45
≥3	65	27	35	22	100	25	5031	24
Prepregnancy BMI (kg/m2)
<19	17	7	20	13	37	9	1835	12
19–24	169	72	115	73	284	72	11,019	72
25–29	37	16	16	10	53	14	1836	12
≥30	13	5	6	4	19	5	589	4
Mother’s race/ethnicity
White	104	43	90	56	194	49	13,437	66
Black	113	47	52	33	165	41	4936	24
Hispanic	4	2	3	2	7	2	678	3
Asian	11	5	9	6	20	5	783	4
Multiracial/other	8	3	5	3	13	3	597	3
Mother’s place of birth
Southeastern U.S.	97	41	48	30	145	36	4508	26
California	82	34	63	40	145	36	5885	34
U.S. other than Southeast or California	46	19	36	23	82	21	5194	30
Outside U.S.	14	6	12	7	26	7	1880	11
Mother’s occupation
Housewife	138	58	84	53	222	56	9170	57
Factory/household	24	10	11	7	35	9	1137	7
Secretary/clerical	63	26	49	31	112	28	3907	25
Professional	14	6	15	9	29	7	1726	11
Mother’s education
Not high school graduate	54	22	22	14	76	19	3341	19
High school graduate/trade school	105	44	55	35	160	40	6661	38
Some college	81	34	82	51	163	41	7549	43
Adequacy of prenatal care
More than adequate	35	15	16	10	51	13	2927	15
Adequate	105	44	93	59	198	50	9099	46
Intermediate	11	4	13	8	24	6	1628	8
Inadequate	88	37	36	23	124	31	6059	31
Maternal alcohol consumption
<1 drink/week	129	54	65	41	194	49	6312	30
1–4 drinks/week	93	39	69	43	162	41	12,718	62
≥5 drinks/week	18	7	25	16	43	11	1724	8
Maternal smoking
Currently	78	33	43	27	121	31	5691	36
Not currently	160	67	114	73	274	69	10,313	64
IUGR medications‡
Prescribed	11	5	6	4	17	4	2085	10
Not prescribed	229	95	153	96	382	96	18,669	90
Preeclampsia, eclampsia
Yes	12	5	6	4	18	5	569	3
No	228	95	153	96	381	95	20,185	97
Essential hypertension
Yes	30	13	22	14	52	13	1483	7
No	210	87	137	86	347	87	19,271	93
Father’s occupation
Professional/technical/student	32	14	46	29	78	20	5007	31
Manager/craftsman	49	21	30	19	79	20	3445	22
Clerical/sales/service/military	77	33	48	22	125	32	3779	24
Operative/laborer/unemployed	79	32	34	30	113	29	3691	23
Father’s education
Not high school graduate	52	23	22	15	74	19	2997	18
High school graduate/trade	76	33	35	23	111	29	4607	28
Some college	70	30	52	34	122	32	4329	26
College graduate	33	14	43	28	76	20	4681	28
Child’s sex
Female	133	55	80	50	213	53	9451	49
Male	107	45	79	50	186	47	9927	51

^*Data missing for some characteristics for some study participants.

^†Subjects in stratum 1 are those children who scored below the 10th percentile on a cognitive examination or who failed a hearing examination. Subjects in stratum 2 are a 17% random sample of those who did not fail a hearing examination and scored above the 10th percentile on both cognitive examinations. See text for details.

^‡See text for details.