TABLE 1.
Baseline maternal characteristics between treatment groups1
| Vitamin D supplementation, IU |
||||
| Maternal baseline characteristic (n = 301) | 400 (n = 98) | 2000 (n = 102) | 4000 (n = 101) | P |
| Race, n (%) | 0.753 | |||
| African Americans | 25 (25.5) | 29 (28.4) | 26 (25.7) | |
| Hispanics | 41 (41.8) | 47 (46.1) | 41 (40.6) | |
| Caucasians | 32 (32.7) | 26 (25.5) | 34 (33.7) | |
| BMI, kg/m2 | 28.3 ± 7.12 | 28.4 ± 7.4 | 26.8 ± 5.6 | 0.467 |
| Obesity (BMI ≥30), n (%) | 31 (34.8) | 33 (35.1) | 25 (27.4) | 0.458 |
| Age, y | 27.6 ± 5.8 | 28.2 ± 5.4 | 27.2 ± 5.5 | 0.426 |
| Serum 25(OH)D, nmol/L | 62.8 ± 27.4 | 56.4 ± 21.5 | 58.2 ± 21.3 | 0.214 |
| Vitamin D inadequacy,3 n (%) | 31 (31.6) | 43 (42.2) | 35 (35.4) | 0.291 |
| Calcium intake, mg/d | 1089 ± 631 | 1004 ± 546 | 1103 ± 573 | 0.520 |
| Physical activity, h/d | 2.1 ± 3.4 | 1.5 ± 1.5 | 1.7 ± 2.7 | 0.880 |
| Season at study entry, n (%) | 0.813 | |||
| April through September | 50 (51.0) | 53 (52.0) | 48 (47.5) | |
| October through March | 48 (49.0) | 49 (48.0) | 53 (52.5) | |
| Compliance,4 n (%) | 53 (54.1) | 57 (55.9) | 55 (54.5) | 0.964 |
| Gestational visit, wk | 15.9 ± 1.3 | 15.9 ± 1.2 | 16.0 ± 1.2 | 0.664 |
| Postpartum visit, wk | 2.9 ± 2.1 | 2.8 ± 2.0 | 2.7 ± 2.0 | 0.332 |
1
There were no significant differences in baseline characteristics between treatment groups. Overall comparisons between treatment groups were based on a Kruskal-Wallis rank-sum test for continuous variables (mean ± SD) and a Fisher’s exact test for categorical variables [n (%)]. 25(OH)D, 25-hydroxyvitamin D.
2
Mean ± SD (all such values).
3
25(OH)D concentration <50 nmol/L (<20 ng/mL).
4
Taking ≥75% of vitamin D pills during the course of the study.