Table 2. Maternal vitamin D status and risk of small for gestational age in women at high risk for preeclampsia.
| Serum 25(OH)D categories | Non-SGA | SGA | Adjusted risk ratio* | 95% CI | Adjusted risk difference*,† | 95% CI |
|---|---|---|---|---|---|---|
|
| ||||||
| n (incidence %) | ||||||
| Overall | ||||||
| <30 nmol/L | 71 (79.8) | 18 (20.2) | Reference | Reference | ||
| 30-49 nmol/L | 171 (85.1) | 30 (14.9) | 0.71 | 0.42 - 1.19 | -5.8 | -15.0-3.4 |
| 50-74 nmol/L | 218 (87.9) | 30 (12.1) | 0.57 | 0.33 - 0.99 | -8.4 | -17.7-0.9 |
| ≥75 nmol/L | 229 (90.2) | 25 (9.8) | 0.46 | 0.24 - 0.87 | -10.8 | -20.6- -0.9 |
| <50 nmol/L‡ | 242 (83.5) | 48 (16.6) | Reference | Reference | ||
| ≥50 nmol/L | 447 (89.0) | 55 (11.0) | 0.66 | 0.43 - 1.01 | -5.3 | -11.0-0.36 |
| Maternal race§ | ||||||
| Whites‡,║ | ||||||
| <50 nmol/L | 37 (75.5) | 12 (24.5) | Reference | Reference | ||
| ≥50 nmol/L | 229 (92.0) | 20 (8.0) | 0.32 | 0.17 - 0.63 | -15.5 | -27.7- -3.3 |
| Blacks | ||||||
| <50 nmol/L | 205 (85.1) | 36 (14.9) | Reference | Reference | ||
| ≥50 nmol/L | 218 (86.2) | 35 (13.8) | 0.86 | 0.55 - 1.34 | -2.1 | -8.2-4.1 |
| Maternal obesity status§ ¶ | ||||||
| Nonobese‡ | ||||||
| <50 nmol/L | 101 (76.5) | 31 (23.5) | Reference | Reference | ||
| ≥50 nmol/L | 278 (89.1) | 34 (10.9) | 0.50 | 0.31 - 0.82 | -11.1 | -19.7- -2.5 |
| Obese | ||||||
| <50 nmol/L | 141 (89.2) | 17 (10.8) | Reference | Reference | ||
| ≥50 nmol/L | 169 (89.0) | 21 (11.1) | 1.09 | 0.58 - 2.04 | 0.8 | -5.5-7.1 |
25(OH)D, 25-hydroxyvitamin D; SGA, small-for-gestational-age; CI, confidence interval.
*
Adjusted for latitude, obesity status, race, treatment group, and risk group.
†
Per 100 live births.
‡
P=0.001 for difference in incidence of SGA by 25(OH)D categories.
§
Synergy index for additive interaction = 0.43 (95% CI: 0.22, 0.64) by race and 0.50 (95% CI: 0.28, 0.71) by obese status
║
n=243 non-Hispanic white, n=53 Hispanic white, n=2 American Indian/Alaskan.
¶
Nonobese = BMI <30 kg/m2; Obese = BMI ≥30 kg/m2.