Table 1. Study sample characteristics (complete cases for exposures, outcomes, confounders and mediators n = 2958) and ALSPAC sample characteristics (with dietary iron intake data n = 12116).
| Complete case sample | ALSPAC sample (with dietary data) | |
| Dietary iron intake # (mg/day) (m, sd * ) | 10.7 (3.2) | 10.4 (3.4) |
| Dietary iron intake <UK RNI ## (%, 95% CI ** ) | 89.2 (88.0, 90.3) | 90.3 (89.7, 90.8) |
| Dietary iron intake <UK LRNI ### (%, 95% CI) | 18.0 (16.7, 19.5) | 25.0 (24.2, 25.8) |
| Dietary vitamin C intake ## (mg/day) (m, sd) | 85.9 (34.5) | 80.1 (35.3) |
| Age of mother (yrs) (m, sd) | 29.5 (4.2) | 28.5 (4.8) |
| Pre-pregnancy BMI (kg/m2) (m, sd) | 22.8 (3.5) | 22.9 (3.6) |
| Total energy intake (kj) (m, sd) | 7,483 (1,908) | 7,415 (2,081) |
| Smoking in pregnancy (%, 95% CI ** ) | 15.4 (14.1, 16.7) | 25.2 (24.4, 26.0) |
| Caucasian (%, 95% CI) | 98.8 (98.4, 99.2) | 97.5 (97.2, 97.8) |
| University degree (%, 95% CI) | 18.6 (17.2, 20.0) | 13.8 (13.1, 14.4) |
| Vegetarian (%, 95% CI) | 6.1 (5.3, 7.0) | 5.2 (4.8, 5.6) |
| Primigravida (%, 95% CI) | 48.8 (47.0, 50.6) | 44.8 (43.9, 45.7) |
| Early pregnancy maternal anemia (<11 g/dL) (%, 95% CI) | 4.4 (3.7, 5.1) | 5.1 (4.6, 5.5) |
| Report taking iron supplements Before 32 wks gestation (%, 95% CI) | 44.9 (43.1, 46.7) | 47.5 (46.6, 48.4) |
| Child gender (male) (%, 95% CI) | 50.8 (49.0, 52.6) | 51.5 (50.6, 52.4) |
| Birthweight (g) (m, sd) | 3,448 (499) | 3,411 (544) |
| Gestational age (wks) (m, sd) | 39.6 (1.6) | 39.5 (1.8) |
# Food frequency questionnaire at 32 weeks gestation.
## UK Reference Nutrient Intake (14.8 mg/day).
### UK Lower Reference Nutrient Intake (8 mg/day).
Mean, standard deviation.
95% confidence intervals.