Table 1.
25-Hydroxyvitamin D (25(OH)D) status and confounding variables in the total sample and stratified by gestational diabetes mellitus (GDM) status, WHO 2013 criteria. Values are mean (95% confidence interval) or (numbers (%)).
| GDM (WHO 2013) | p | |||
|---|---|---|---|---|
| Yes | No | |||
| n = 745 | n = 235 | n = 510 | ||
| Status at inclusion (15 GWi) | ||||
| Overall mean 25(OH)D (nmol/L) | 50.2 (48.3, 52.1) | 47.7 (44.0, 51.3) | 51.4 (49.2, 53.7) | 0.07 |
| 25(OH)D < 50 nmol/L (n (%)) | 389 (52) | 141 (60) | 248 (49) | 0.01 |
| 25(OH)D status during pregnancya | ||||
| Consistently sufficient (n (%)) | 417 (57) | 109 (47) | 308 (61) | <0.01 |
| Decreasing (n (%)) | 63 (8.6) | 22 (9.6) | 41 (8.1) | 0.50 |
| Increasing (n (%)) | 145 (20) | 55 (24) | 90 (18) | 0.06 |
| Consistently deficient (n (%)) | 111 (15) | 44 (19) | 67 (13) | 0.03 |
| Prepregnancy maternal status | ||||
| Age (years) | 29.8 (29.5, 30.2) | 30.3 (29.6, 30.9) | 29.6 (29.2, 30.1) | 0.12 |
| Ethnicity (n (%)) | ||||
| Europe | 346 (46.4) | 82 (35) | 264 (52) | <0.01 |
| South Asia | 191 (25.6) | 81 (35) | 110 (22) | <0.01 |
| Middle East and North Africa | 115 (15.4) | 41 (17) | 74 (15) | 0.49 |
| Sub-Saharan Africa | 53 (7.1) | 20 (8.5) | 33 (6.5) | 0.32 |
| East Asia | 40 (5.4) | 11 (4.7) | 29 (5.7) | 0.57 |
| Parity (n (%)) | ||||
| Para 0 | 340 (46) | 104 (44) | 236 (46) | 0.61 |
| Para 1 | 256 (34) | 73 (31) | 183 (36) | 0.18 |
| Para ≥ 2 | 149 (20) | 58 (25) | 91 (18) | 0.03 |
| Education (years) (n (%))a | ||||
| <10 | 122 (16) | 50 (21) | 72 (14) | 0.02 |
| 10–12 | 293 (40) | 100 (43) | 193 (38) | 0.20 |
| >12 | 324 (44) | 84 (36) | 240 (48) | <0.01 |
| Prepregnancy BMIii (kg/m2)a | 24.5 (24.2, 24.9) | 25.9 (25.2, 26.6) | 23.9 (23.5, 24.3) | <0.01 |
| Status at inclusion | ||||
| Gestational week | 15.1 (14.9, 15.4) | 15.2 (14.7, 15.6) | 15.1 (14.8, 15.4) | 0.74 |
| Sum of skinfolds (mm)b | 72.0 (70.6, 73.5) | 77.0 (74.3, 79.8) | 69.8 (68.1, 71.5) | <0.01 |
| Season for 25(OH)D measurement (n (%)) | ||||
| Summer | 347 (47) | 130 (55) | 217 (43) | <0.01 |
| Winter | 398 (53) | 105 (45) | 293 (57) | <0.01 |
| Status at 28 GW | ||||
| Gestational weekc | 28.3 (28.2, 28.4) | 28.2 (28.0, 28.3) | 28.3 (28.2, 28.4) | 0.20 |
| ΔSum of skinfolds (15 to 28 GW) (mm)d | 5.8 (4.8, 6.8) | 6.2 (4.5, 7.9) | 5.6 (4.3, 6.8) | 0.58 |
| Weight gain (prepregnant to 28 GW) (kg) | 8.7 (8.3, 9.0) | 8.8 (8.1, 9.4) | 8.6 (8.2, 9.0) | 0.71 |
| Dietary clusters (n (%))a | ||||
| Healthy | 239 (33) | 54 (23) | 185 (37) | <0.01 |
| Unhealthy | 493 (67) | 179 (77) | 314 (63) | <0.01 |
iGW: gestational week derived from the 1st day of the woman's last menstrual period; iiBMI: body mass index; amissing information of 5–13 women; b n = 681; cmissing information of 1–4 women; d n = 649. Consistently sufficient: 25(OH)D ≥ 37 nmol/L at 15 and 28 GW. Decreasing: 25(OH)D ≥ 37 nmol/L at 15 GW and <37 nmol/L at 28 GW. Increasing: 25(OH)D < 37 nmol/L at 15 GW and ≥37 nmol/L at 28 GW. Consistently deficient: 25(OH)D < 37 nmol/L at 15 and 28 GW. p values for the differences between GDM and non-GDM. Bold numbers indicate p values < 0.05. Independent t-test or two-sample test of proportions.