TABLE 1.

Maternal and Infant Characteristics of Cases and Controls Based on the 1988 National Maternal and Infant Health Survey

	Infant Deaths
	Neonatal	Post neonatal	Total	Controls
No.	2667	1598	4265	7293
N SUDAAN estimate	19,365	12,166	31,531	3,036,202
	%	%	%	%
Maternal self-reported prepregnancy BMI (kg/m2)
<18.5 (underweight)	11	12	11	10
18.5–24.9 (normal weight)	62	64	63	68
25–29.9 (overweight)	18	17	17	16
≥30 (obese)	9	8	9	6
Self-reported weight gain during pregnancy (kg/wk)
<0.15	17	14	16	8
0.15–0.29	29	31	30	30
0.30–0.44	25	30	27	34
≥0.45	29	25	27	27
Maternal race
White	69	70	69	79
African American	28	27	27	16
Others	3	4	3	5
Maternal age at pregnancy (y)
<20	17	18	17	12
20–24	26	32	28	28
25–29	29	27	28	32
30–34	20	16	18	21
≥35	9	7	8	8
Maternal education (y)
<9	28	28	28	32
9–12	47	51	49	41
>12	25	21	23	27
Maternal smoking during pregnancy
Yes	33	41	36	30
No	67	60	64	71
Sex
Male	56	57	57	52
Female	44	43	43	48
Live birth order
1	42	34	39	42
2	30	32	31	33
≥3	27	34	30	25
Plurality
Singleton	87	95	90	98
Multiple birth	13	5	10	2
Reported birth defects
No	86	93	89	99
Yes	14	7	11	1
Birth weight (g)
<2500	73	30	56	6
≥2500	27	70	44	94
Preterm birth
Yes	71	31	55	9
No	29	69	45	91