Table 1.
Characteristics of mothers and infants with 25‐hydroxyvitamin D levels assayed
| N | Pregnancy | Cord blood | Maternal 4 months | Infant 4 months | ||
|---|---|---|---|---|---|---|
| 608 | 345 | 333 | 322 | |||
| Mother | Age | Median (IQR) | 31.4 (27.9–34.8) | 32.6 (29.4–35.7) | 32.8 (29.8–36.0) | |
| Gestationa | Median (IQR) | 26.9 (26.0–28.7) | ||||
| Maternal skin type I | N (%) | 73 (12%) | 37 (11%) | 43 (13%) | ||
| Maternal skin type II | N (%) | 182 (30%) | 110 (32%) | 109 (33%) | ||
| Maternal skin type III | N (%) | 310 (51%) | 178 (52%) | 162 (49%) | ||
| Maternal skin type IV | N (%) | 43 (7%) | 20 (6%) | 19 (6%) | ||
| Time outside:<15 mina | N (%) | 31 (5%) | 21 (6%) | 10 (3%) | ||
| Time outside: 15–30 min | N (%) | 185 (30%) | 111 (32%) | 80 (24%) | ||
| Time outside: 30 min–2 hrs | N (%) | 316 (52%) | 180 (52%) | 193 (59%) | ||
| Time outside: >2 hrs | N (%) | 76 (12%) | 33 (10%) | 45 (14%) | ||
| Travelled abroad | N (%) | 104 (17%) | 53 (15%) | 38 (12%) | ||
| Smokes | N (%) | 65 (11%) | 29 (8%) | 32 (10%) | ||
| Vitamin D from foodsa | Median (IQR) | 2.8 (1.7–4.1) | 2.8 (1.7–4.0) | 3 (1.9–4.4) | ||
| Vitamin D supplements | N (%) | 443 (73%) | 254 (74%) | 137 (42%) | ||
| Total vitamin D intake | Median (IQR) | 12.1 (6.0–13.6) | 12.1 (6.8–13.6) | 5.1 (2.5–12.6) | ||
| IMD quintile Ib | N (%) | 38 (6%) | 22 (7%) | 26 (8%) | 24 (8%) | |
| IMD quintile II | N (%) | 72 (12%) | 40 (12%) | 44 (13%) | 43 (14%) | |
| IMD quintile III | N (%) | 105 (18%) | 49 (14%) | 60 (18%) | 56 (18%) | |
| IMD quintile IV | N (%) | 127 (21%) | 78 (23%) | 69 (21%) | 70 (22%) | |
| IMD quintile V | N (%) | 257 (43%) | 149 (44%) | 128 (39%) | 123 (39%) | |
| Infant | Malea | N (%) | 108 (53%) | 159 (50%) | ||
| Gestation | Median (IQR) | 40 (39–41) | ||||
| Birth weight | Median (IQR) | 3.5 (3.2–3.9) | ||||
| Breast feedingc | N (%) | 108 (34%) | ||||
| Formula feeding | N (%) | 126 (39%) | ||||
| Mixed feeding | N (%) | 85 (27%) | ||||
| Supplements | N (%) | 58 (18%) |
a
1 incomplete questionnaire
b
9 missing valid postcodes
c
3 missing