TABLE 2.
Blood collection information
| Characteristic | Controls (n = 1975) | PE (n = 169) | P valuea |
|---|---|---|---|
| Serum 25(OH)D concentration, nmol/L | |||
| Mean ± SD | 52.3 ± 17.2 | 47.2 ± 17.7 | .0002 |
| Median (IQR) | 51.9 (39.9–62.3) | 46.5 (35.5–57.5) | |
| Proportion <30 | 169 (9) | 27 (16) | .0001 |
| 30–49.9 | 740 (37) | 76 (45) | |
| ≥50 | 1066 (54) | 66 (39) | |
| Gestational age at blood collection, wk | |||
| Mean ± SD | 13.6 ± 3.0 | 13.8 ± 3.0 | .41 |
| Season | |||
| Spring | 479 (24) | 38 (22) | .58 |
| Summer | 384 (19) | 39 (23) | |
| Autumn | 567 (29) | 43 (25) | |
| Winter | 545 (27) | 49 (29) | |
| Year | |||
| 2002 through 2005 | 669 (34) | 71 (42) | .03 |
| 2006 through 2010 | 1306 (66) | 98 (58) | |
Values are no. (%) unless otherwise specified.
IQR, interquartile range; PE, preeclampsia; 25(OH)D, 25-hydroxyvitamin D.
a
P<.05 comparing mothers with PE and mothers with no PE, using t test for continuous variables and χ2 tests for differences for categorical variables.