TABLE 1—

Weighted Descriptive Characteristics for Samples of National Longitudinal Survey of Youth (NLSY) Children Born Between 1990 and 1996

					Discordant Sibling Samplea
	Total Sample (n = 1984)		Sibling Sample (n = 969)		Group 1 (n = 19)		Group 2 (n = 49)
	Mean	SD	Mean	SD	Mean	SD	Mean	SD
Prenatal maternal variables
Prenatal WIC participation, %	12	33	12	32	68	47	55	50
Prenatal food stamps, %	10	31	09	29	57	50	34	47
Total income (in 1000s)	47.82	26.67	50.05	26.50	20.39	19.07	18.19	18.34
Drank during pregnancy, %	52	50	52	50	40	50	35	48
Smoked during pregnancy, %	24	43	19	39	46	50	29	46
Maternal characteristics and background
Armed Forces Qualifying Test score	74.21	19.47	76.82	18.77	63.08	20.52	54.06	20.13
Self-esteem score (1980)	1.76	0.41	1.75	0.40	1.78	0.34	1.81	0.50
Deviant behavior score (1980)	1.14	1.18	1.11	1.19	1.15	1.27	1.34	1.38
Prenatal urban residence, %	82	38	85	35	80	40	80	40
Prenatal maternal education, y	13.75	2.45	14.04	2.28	11.82	1.67	11.82	1.72
Parents' educational level, y	12.06	2.91	12.46	2.87	10.49	3.03	9.95	2.68
Worked at age of 14 years, %	51	50	47	50	21	41	40	49
Lack of literary supports, %	05	22	04	20	04	20	10	33
No. of siblings	3.33	2.20	3.26	2.22	4.04	2.80	3.95	2.44
Child demographics
Black, %	11	31	09	29	37	49	31	47
Hispanic, %	06	24	06	24	13	34	18	38
Male, %	50	50	51	50	65	48	48	50
Gestational length, wk	38.38	1.97	38.40	1.83	38.6	1.72	38.14	1.89
Outcome variable: birthweight, oz	119.71	21.01	120.83	20.21	115.84	19.51	116.18	20.66

Note. The total sample consists of all NLSY children who were born between 1990 and 1996 and had valid information on prenatal WIC participation. The sibling sample consists of NLSY children who were born between 1990 and 1996 and had at least one sibling who was born in the same time period.

^aOf the discordant sibling groups, 19 followed the pattern of WIC receipt in the first pregnancy but not in subsequent pregnancies (Group 1), and 49 followed the pattern of nonreceipt of WIC in the first pregnancy but not in subsequent pregnancies (Group 2).