Table 3.
Predictors of Infant Vitamin D Status at 4 Weeks of Age
| Infants’ Serum 25(OH)D Concentration Status | |||||||
|---|---|---|---|---|---|---|---|
| Number (%) | |||||||
| Variables | N | Serum 25(OH)D (Mean ± SD) | p-value for ANOVA | < 25 nmol/L | 25 – <50 nmol/L | ≥ 50 nmol/L | p-value for difference* |
| All subjects vitamin D status | 87 | 41.0 ± 16.3 | 18.7 ± 3.5 | 39.2 ± 7.0 | 63.5 ± 10.1 | ||
| Ethnicity | |||||||
| White | 69 | 43.5 ± 15.6 | 0.008 | 8 (12%) | 43 (62%) | 18 (26%) | 0.005 |
| African-American | 9 | 26.9 ± 14.4 | 6 (67%) | 2 (22%) | 1 (11%) | ||
| Other | 9 | 35.7 ± 16.1 | 2 (22%) | 6 (67%) | 1 (11%) | ||
| Maternal Education Status | |||||||
| Completed 4 Year College | 58 | 42.4 ± 17.1 | 0.25 | 9 (16%) | 33 (57%) | 16 (28%) | 0.29 |
| Did Not Complete 4 Year College | 29 | 38.1 ± 14.5 | 7 (24%) | 18 (62%) | 4 (14%) | ||
| Maternal Vit D Supplementation | |||||||
| Any Supplementation | 71 | 40.0 ± 15.7 | 0.12 | 13 (18%) | 43 (61%) | 15 (21%) | 0.54 |
| No Supplementation | 11 | 48.2 ± 17.4 | 1 (9%) | 6 (55%) | 4 (36%) | ||
| Infant Vit D Supplementation | |||||||
| Supplemented Prior to 4 Weeks of Age | 3 | 51.5 ± 34.0 | 0.26 | 1 (33%) | 0 (0%) | 2 (67%) | 0.07 |
| Not Supplemented Prior to 4 Weeks of Age | 84 | 40.6 ± 15.6 | 15 (18%) | 51 (61%) | 18 (21%) | ||
| Season | |||||||
| Winter/Spring | 31 | 34.0 ± 14.7 | 0.002 | 10 (32%) | 17 (55%) | 4 (13%) | 0.03 |
| Summer/Fall | 56 | 44.9 ± 15.9 | 6 (11%) | 34 (61%) | 16 (29%) | ||
| Sun Exposure Time | |||||||
| Lowest quartile (< 0.67 hrs) | 22 | 34.1 ± 12.6 | 0.003 | 6 (27%) | 14 (64%) | 2 (9%) | 0.03 |
| Highest quartile (> 5.83 hrs) | 19 | 48.3 ± 16.3 | 1 (5%) | 10 (53%) | 8 (42%) | ||
| Sun Exposure (BSA) | |||||||
| Lowest quartile (< 12%) | 22 | 36.4 ± 16.1 | 0.04 | 7 (32%) | 11 (50%) | 4 (18%) | 0.03 |
| Highest quartile (> 43%) | 17 | 46.7 ± 12.8 | 0 (0%) | 13 (77%) | 4 (24%) | ||
| Sun Index | |||||||
| Lowest quartile (< 10.75) | 22 | 32.4 ± 12.8 | < 0.001 | 8 (36%) | 12 (55%) | 2 (9%) | 0.01 |
| Highest quartile (> 161.5) | 21 | 49.0 ± 14.7 | 1 (5%) | 12 (57%) | 8 (38%) | ||
| Sunscreen Usage | |||||||
| Any sunscreen usage | 1 | 60.0 ± N/A | 0.13 | 0 (0%) | 0 (0%) | 1 (100%) | 0.21 |
| No sunscreen usage | 32 | 35.6 ± 15.6 | 9 (28%) | 17 (53%) | 6 (19%) | ||
| Maternal Vit D Status | |||||||
| Deficient (< 50 nmol/L) | 15 | 35.5 ± 18.7 | 0.08 | 6 (40%) | 5 (33%) | 4 (27%) | 0.04 |
| Insufficient (50 – <75 nmol/L) | 45 | 39.6 ± 15.8 | 8 (18%) | 30 (67%) | 7 (16%) | ||
| Sufficient (≥ 75 nmol/L) | 26 | 46.7 ± 15.0 | 2 (8%) | 15 (58%) | 9 (35%) | ||
For vit D level, mean comparisons made with ANOVA. For tests of proportions, differences were tested using chi-square or Fisher’s Exact test, as appropriate.