Table 1

Selected maternal characteristics of birth defect cases and controls in the National Birth Defects Prevention Study, 1997-2005
Characteristics of participants Control Neural tube defects Limb deficiencies Oral cleft defects
N = 6698 N = 1170 N = 693 N = 2727
N % N % N % N %
Race-ethnicitya,b,c
Non-Hispanic White 3,989 59.6 596 50.9 388 56.0 1,708 62.6
Non-Hispanic Black 758 11.3 108 9.2 71 10.3 173 6.3
Hispanic 1,464 21.9 377 32.2 190 27.4 640 23.5
Asian/Pacific Islander 197 2.9 25 2.1 14 2.0 81 3.0
Native American/Alaskan 29 0.4 7 0.6 3 0.4 23 0.8
Other 233 3.5 53 4.5 27 3.9 94 3.5
Missing 28 0.4 4 0.3 0 0.0 8 0.3
Maternal Education (years) a,c
<9 years 325 4.9 95 8.1 33 4.8 158 5.8
9-11 years 770 11.5 149 12.7 81 11.7 350 12.8
12 years 1,627 24.3 332 28.4 185 26.7 761 27.9
13-15 years 1,784 26.6 328 28.0 197 28.4 724 26.6
16 years or more 2,096 31.3 252 21.5 188 27.1 708 26.0
Missing 96 1.4 14 1.2 9 1.3 26 1.0
Age at Delivery (years) a,c
<18 years old 246 3.7 43 3.7 30 4.3 88 3.2
18-19 years old 465 6.9 94 8.0 53 7.7 190 7.0
20-24 years old 1,517 22.7 256 21.9 175 25.3 694 25.5
25-29 years old 1,781 26.6 381 32.6 172 24.8 728 26.7
30-34 years old 1,741 26.0 244 20.9 179 25.8 615 22.6
35-39 years old 810 12.1 111 9.5 73 10.5 342 12.5
40-44 years old 126 1.9 38 3.3 11 1.6 64 2.4
45-49 years old 11 0.2 3 0.3 0 0.0 6 0.2
>49 Years old 1 0.0 0 0.0 0 0.0 0 0.0
Study Centera,b,c
Arkansas 836 12.5 145 12.4 66 9.5 306 11.2
California 839 12.5 232 19.8 114 16.5 437 16.0
Georgia 749 11.2 138 11.8 73 10.5 302 11.1
Iowa 849 12.7 73 6.2 89 12.8 382 14.0
Massachusetts 568 8.5 68 5.8 78 11.3 189 6.9
North Carolina 596 8.9 70 6.0 49 7.1 246 9.0
New Jersey 772 11.5 162 13.9 92 13.3 343 12.6
New York 720 10.8 138 11.8 73 10.5 328 12.0
Texas 405 6.1 70 6.0 13 1.9 99 3.6
Utah 364 5.4 74 6.3 46 6.6 95 3.5
Maternal Body Mass Indexa,c (kg/m2)
Underweight (BMI <18) 353 5.3 48 4.1 38 5.5 183 6.7
Normal weight (18.5 -25) 3,585 53.5 544 46.5 337 48.6 1,376 50.5
Overweight (25–30) 1,443 21.5 243 20.8 164 23.7 569 20.9
Obese (≥30) 1,037 15.5 259 22.1 121 17.5 479 17.6
Missing 280 4.2 76 6.5 33 4.8 120 4.4
Folic Acid Supplement Usec
No 3,053 45.6 552 47.2 305 44.0 1,330 48.8
Yes 3,480 52.0 577 49.3 366 52.8 1,340 49.1
Missing 165 2.5 41 3.5 22 3.2 57 2.1

a Statistically significant difference in covariate distribution between control mothers and mothers of offspring with a NTD.

b Statistically significant difference in covariate distribution between control mothers and mothers of offspring with a limb malformation.

c Statistically significant difference in covariate distribution between control mothers and mothers of offspring with an orofacial cleft.

Huber et al.

Huber et al. Nutrition Journal 2013 12:34   doi:10.1186/1475-2891-12-34

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