Table 3.
Prepregnancy B Vitamin Intake and Relative Risks of Spontaneous Abortion
| Quintile of Intake (median, μg/day) | Cases/Total | % | Multivariate-Adjusted RR (95% CI)* |
|---|---|---|---|
| Thiamin (B1) | |||
| Q1 (1.3) | 561/3172 | 17.7 | 1.00 (Ref) |
| Q2 (1.7) | 552/3179 | 17.4 | 1.00 (0.89, 1.11) |
| Q3 (2.4) | 549/3210 | 17.1 | 0.98 (0.88, 1.10) |
| Q4 (3.2) | 536/3204 | 16.7 | 0.95 (0.85, 1.06) |
| Q5 (5.1) | 558/3185 | 17.5 | 0.96 (0.86, 1.06) |
| P for Trend | 0.33 | ||
| Riboflavin (B2) | |||
| Q1 (1.6) | 588/3215 | 18.3 | 1.00 (Ref) |
| Q2 (2.2) | 531/3142 | 16.9 | 0.93 (0.84, 1.04) |
| Q3 (3.0) | 544/3231 | 16.8 | 0.94 (0.85, 1.05) |
| Q4 (4.0) | 549/3178 | 17.3 | 0.96 (0.86, 1.06) |
| Q5 (6.2) | 544/3184 | 17.1 | 0.90 (0.81, 1.00) |
| P for Trend | 0.13 | ||
| Niacin (B3) | |||
| Q1 (20.1) | 555/3175 | 17.5 | 1.00 (Ref) |
| Q2 (25.3) | 552/3187 | 17.3 | 1.01 (0.91, 1.12) |
| Q3 (33.3) | 533/3198 | 16.7 | 0.97 (0.87, 1.08) |
| Q4 (40.7) | 535/3205 | 16.7 | 0.96 (0.86, 1.07) |
| Q5 (53.0) | 581/3185 | 18.2 | 1.00 (0.90, 1.11) |
| P for Trend | 0.84 | ||
| Pantothenic Acid (B5) † | |||
| Q1 (4.0) | 548/3189 | 17.2 | 1.00 (Ref) |
| Q2 (5.0) | 571/3331 | 17.1 | 0.99 (0.89, 1.11) |
| Q3 (6.1) | 501/3041 | 16.5 | 0.96 (0.86, 1.08) |
| Q4 (11.5) | 528/3189 | 16.6 | 0.95 (0.85, 1.06) |
| Q5 (18.1) | 608/3200 | 19.0 | 1.04 (0.94, 1.15) |
| P for Trend | 0.39 | ||
| Vitamin B6† | |||
| Q1 (1.8) | 528/2956 | 17.9 | 1.00 (Ref) |
| Q2 (2.3) | 615/3562 | 17.3 | 1.00 (0.90, 1.11) |
| Q3 (3.4) | 537/3084 | 17.4 | 1.00 (0.90, 1.12) |
| Q4 (4.8) | 529/3170 | 16.7 | 0.94 (0.84, 1.05) |
| Q5 (13.7) | 547/3178 | 17.2 | 0.95 (0.85, 1.05) |
| P for Trend | 0.25 | ||
| Vitamin B12† | |||
| Q1 (4.0) | 746/4026 | 18.5 | 1.00 (Ref) |
| Q2 (6.0) | 293/1739 | 16.9 | 0.91 (0.81, 1.03) |
| Q3 (9.0) | 580/3622 | 16.0 | 0.88 (0.80, 0.97) |
| Q4 (12.0) | 588/3220 | 18.3 | 1.01 (0.91, 1.11) |
| Q5 (19.0) | 549/3343 | 16.4 | 0.87 (0.79, 0.96) |
| P for Trend | 0.04 | ||
RR, relative risk; CI, confidence interval.
*
Adjusted for age (continuous), energy intake (continuous), BMI (<18.5, 18.5–24.9, 25–29.9, ≥30, and missing), smoking status (never, former, current, and missing), physical activity (< 3, 3–8.9, 9–17.9, 18–26.9, 27–41.9, >42 MET-h/wk, and missing), year of pregnancy, history of infertility (no, yes, and missing), marital status (married, not married), and race (white, other).
†
1,500 pregnancies with missing values.