TABLE 3.
Total vitamin A and vitamin D intake in pregnancy and RR estimates (95% CIs) for current asthma at age 7 y1
| Quintiles of intake | Cases/total n | Prevalence, % | Crude RR | Adjusted RR2 |
|---|---|---|---|---|
| Total vitamin A (RAEs/d) | ||||
| Q1 (≤779) | 506/12,331 | 4.1 | 1 (ref) | 1 (ref) |
| Q2 (780–1102) | 445/12,323 | 3.6 | 0.88 (0.78, 1.00) | 0.92 (0.80, 1.05) |
| Q3 (1103–1479) | 475/12,331 | 3.9 | 0.94 (0.83, 1.06) | 0.99 (0.86, 1.13) |
| Q4 (1480–2030) | 520/12,345 | 4.2 | 1.03 (0.91, 1.16) | 1.08 (0.93, 1.24) |
| Q5 (≥2031) | 600/12,346 | 4.9 | 1.18 (1.05, 1.33) | 1.21 (1.05, 1.40) |
| P-trend | <0.001 | 0.001 | ||
| Total vitamin D (µg/d) | ||||
| Q1 (≤3.5) | 531/12,089 | 4.4 | 1 (ref) | 1 (ref) |
| Q2 (3.6–5.7) | 485/12,487 | 3.9 | 0.88 (0.78, 1.00) | 0.90 (0.79, 1.02) |
| Q3 (5.8–8.6) | 496/12,393 | 4.0 | 0.91 (0.81, 1.03) | 0.89 (0.77, 1.03) |
| Q4 (8.7–13.5) | 556/12,329 | 4.5 | 1.03 (0.91, 1.15) | 0.96 (0.82, 1.12) |
| Q5 (≥13.6) | 478/12,378 | 3.9 | 0.88 (0.78, 0.99) | 0.81 (0.67, 0.97) |
| P-trend | 0.46 | 0.03 | ||
1 n = 61,676. RRs are from a log binomial regression model. Q, quintile; RAE, retinol activity equivalent; ref, reference.
2Adjusted for maternal total intakes of vitamins A or D (mutual adjustment), vitamin E, vitamin C, folate, and sum of n–3 fatty acids (all in quintiles) and total energy intake (continuous); the following maternal prenatal factors: age at delivery (continuous), parity (0, 1, or ≥2), education (less than high school, high school, ≤4 y of college/university, or >4 y of college/university), prepregnancy BMI (kg/m2; <18.5, 18.5–24.9, 25.0–29.9, or ≥30), history of asthma (no or yes), history of atopy (no or yes), and smoking in pregnancy (no, quit, or yes); and the following mediators: birth weight (<2500, 2500–4500, or ≥4500 g) and prematurity (no or yes). Missing values in covariates were handled by multiple imputation (m = 10) by using chained equations.