TABLE 1.
United States women of childbearing age, 2001–2006
| Characteristic | Pregnant (n = 928) (95% CI) |
Nonpregnant (n = 5173) (95% CI) |
P value |
|---|---|---|---|
| Age, y | < .001 | ||
| 13–19 (n = 2710) | 9% (7–12) | 21% (20–23) | |
| 20–34 (n = 2203) | 78% (73–82) | 44% (41–46) | |
| 35–44 (n = 1188) | 13% (10–18) | 35% (32–37) | |
| Race | < .001 | ||
| NH white (n = 2296) | 56% (50–62) | 65% (62–69) | |
| NH black (n = 1572) | 16% (12–22) | 13% (11–16) | |
| Hispanic (n = 1969) | 20% (16–26) | 16% (13–18) | |
| Other (n = 264) | 8% (6–10) | 6% (4–7) | |
| Poverty-income ratio | .03 | ||
| ≤1 (n = 1650) | 25% (20–30) | 18% (17–20) | |
| >1 (n = 4182) | 71% (65–76) | 78% (76–79) | |
| Unknown (n = 269) | 4% (2–8) | 4% (3–5) | |
| Gestational age | - | ||
| First trimester (n = 198) | 29% (24–34) | - | |
| Second trimester (n = 331) | 31% (26–36) | - | |
| Third trimester (n = 312) | 30% (25–36) | - | |
| Unknown (n = 87) | 10% (7–15) | - | |
| Vitamin D supplement dose (IU) | < .001 | ||
| 0 (n = 4268) | 28% (22–34) | 68% (66–70) | |
| 1–399 (n = 157) | 7% (5–10) | 3% (2–4) | |
| ≥400(n = 1676) | 66% (59–71) | 29% (27–31) | |
| Duration of vitamin D supplement use (d)a | < .001 | ||
| 0 (n = 4269) | 28% (22–34) | 68% (66–70) | |
| 1–30 (n = 251) | 12% (8–17) | 4% (3–5) | |
| 31–180 (n = 423) | 21% (16–26) | 4% (4–5) | |
| ≥181 (n = 1152) | 29% (33–45) | 24% (22–26) | |
| Physical activity in past 30 d | < .001 | ||
| None(n = 1784) | 39% (32–46) | 26% (24–28) | |
| Outdoor (n = 3516) | 53% (45–60) | 62% (59–64) | |
| Indoor/indeterminate only (n = 801) | 8% (5–12) | 12% (11–14) |
CI, confidence interval; NH, non-Hispanic
Weighted to represent total 4 million pregnant and 58 million nonpregnant women in US population.
a
Based on longest duration of use for any current vitamin D-containing supplement; 6 missing/unknown.