Table 2.
Multivariable logistic regression analysis of the determinants of vitamin D deficiency (<30 nmol/L) in the first trimester (T1) of pregnancy. Data is shown for the whole cohort and for the subgroup born in Africa and Asia.
| All Women 1 | Women Born in Africa and Asia 1 | |||||
|---|---|---|---|---|---|---|
| 95% CI | 95% CI | |||||
| OR | Lower | Upper | OR | Lower | Upper | |
| Origin (continent of birth) | ||||||
| North Europe (ref) | ||||||
| America | 5.13 * | 1.01 | 26.15 | |||
| Continental Europe | 4.55 *** | 2.16 | 9.57 | |||
| Asia | 22.09 *** | 11.51 | 42.42 | |||
| Africa | 9.74 *** | 4.09 | 23.18 | |||
| Season T1 | ||||||
| September–November (ref) | ||||||
| March–May | 2.17 ** | 1.35 | 3.49 | 1.22 | 0.62 | 2.41 |
| December–February | 1.91 | 0.29 | 12.38 | 10.01 | 0.63 | 160.02 |
| June–August | 0.59 | 0.13 | 2.63 | 0.22 | 0.03 | 1.72 |
| Vitamin D dietary intake T1 | 0.82 ** | 0.71 | 0.95 | 0.84 | 0.70 | 1.01 |
| Sun-seeking behaviour | ||||||
| Prefer sun (ref) | ||||||
| Prefer both sun and shade | 0.91 | 0.48 | 1.74 | 0.78 | 0.33 | 1.89 |
| Prefer shade | 0.64 | 0.23 | 1.82 | 0.47 | 0.14 | 1.64 |
| Clothing when sunny | ||||||
| Often expose skin (ref) | ||||||
| Seldom expose skin | 1.68 | 0.88 | 3.21 | 1.44 | 0.56 | 3.72 |
| Never expose skin | 6.04 *** | 2.80 | 13.02 | 6.52 *** | 2.56 | 16.60 |
| Vitamin D supplement T1 | ||||||
| No (ref) | ||||||
| Yes | 0.09 *** | 0.05 | 0.17 | 0.04 *** | 0.02 | 0.12 |
| Travel <35° N before T1 | ||||||
| No (ref) | ||||||
| Yes | 0.70 | 0.40 | 1.22 | 0.97 | 0.47 | 1.98 |
| BMI T1 | 1.02 | 0.97 | 1.07 | 1.01 | 0.93 | 1.09 |
| Age | 0.88 *** | 0.83 | 0.93 | 0.89 ** | 0.82 | 0.96 |
| Tobacco use T1 | ||||||
| No (ref) | ||||||
| Yes | 2.18 | 0.88 | 5.39 | 4.71 | 0.42 | 52.74 |
CI, confidence interval; OR, odds ratio; 25(OH)D, 25-hydroxyvitamin D; T1, first trimester; BMI, body mass index; * p < 0.05; ** p < 0.01; *** p < 0.001; 1 Adjusted for parity, employment, education level (all at T1).