Table 2.
Association of Maternal Folic Acid Supplement Use and Neural Tube Defects, Phenotypes, Anencephaly, and Spina Bifida, National Birth Defects Prevention Study, 1998–2003
| No. of Cases | No. of Controls | Crude |
Adjustedab |
|||
| Odds Ratio | 95% Confidence Interval | Odds Ratio | 95% Confidence Interval | |||
| Anencephaly | ||||||
| Nonusers, B3–P1 | 81 | 1,778 | Referent | Referent | Referent | Referent |
| Users, B3–P1 | 38 | 965 | 0.9 | 0.6, 1.3 | 1.2 | 0.8, 1.9 |
| P1 initiator | 61 | 948 | 1.4 | 1.0, 2.0 | 1.7 | 1.2, 2.4 |
| Spina bifida | ||||||
| Nonusers, B3–P1 | 188 | 1,778 | Referent | Referent | Referent | Referent |
| Users, B3–P1 | 97 | 965 | 1.0 | 0.7, 1.2 | 1.4 | 1.0, 1.8 |
| P1 initiator | 100 | 948 | 1.0 | 0.8, 1.3 | 1.1 | 0.9, 1.5 |
Abbreviations: B3, 3 months before pregnancy; P1, first month of pregnancy.
a
The adjusted anencephaly model includes the covariates maternal race and education.
b
The adjusted spina bifida model includes the covariates maternal race, body mass index, and pregnancy intent.