Table 2 The serum 25(OH)D concentration in second trimester stratifed by the characteristics of twin pregnant women
Variables | 25(OH)D concentrations, ng/mL | |||||
|---|---|---|---|---|---|---|
|  | Mean | P-value | Deficiency (< 20) | Insufficiency (20–30) | Sufficiency (≥ 30) | P-value |
Total | 31.1 ± 11.2 |  | 58 (18.7) | 73 (23.5) | 180 (57.9) |  |
Age, years | Â | 0.545 | Â | Â | Â | 0.608 |
< 35 | 31.2 ± 11.4 |  | 52 (18.7) | 63 (22.7) | 163 (58.6) |  |
≥ 35 | 30.0 ± 9.8 |  | 6 (18.2) | 10 (30.3) | 17 (51.5) |  |
Education, years | Â | 0.362 | Â | Â | Â | 0.377 |
≤ 12 | 31.4 ± 11.2 |  | 41 (17.8) | 51 (22.1) | 139 (60.2) |  |
> 12 | 30.1 ± 11.2 |  | 17 (21.2) | 24 (30.0) | 39 (48.8) |  |
Employment status | Â | 0.516 | Â | Â | Â | 0.657 |
Employed | 30.9 ± 11.1 |  | 43 (18.5) | 52 (22.3) | 138 (59.2) |  |
Unemployed | 31.8 ± 11.6 |  | 15 (19.2) | 21 (26.9) | 42 (53.9) |  |
Prepregnancy BMI, kg/m2 | Â | 0.748 | Â | Â | Â | 0.325 |
< 24 | 31.2 ± 11.3 |  | 50 (20.1) | 57 (22.9) | 142 (57.0) |  |
≥ 24 | 30.7 ± 11.0 |  | 10 (16.1) | 19 (30.7) | 33 (53.2) |  |
Parity (number of deliveries) | Â | 0.077 | Â | Â | Â | 0.505 |
0 | 30.4 ± 11.2 |  | 45 (19.8) | 55 (24.2) | 127 (56.0) |  |
≥ 1 | 32.9 ± 11.0 |  | 13 (15.5) | 18 (21.4) | 53 (63.1) |  |
Mode of conception | Â | 0.030 | Â | Â | Â | 0.381 |
Natural conceived | 32.2 ± 11.3 |  | 33 (17.2) | 42 (21.9) | 117 (60.9) |  |
ART | 29.3 ± 10.9 |  | 25 (21.0) | 31 (26.1) | 63 (52.9) |  |
Chorionicity | Â | 0.105 | Â | Â | Â | 0.515 |
Monochorionic | 32.3 ± 11.2 |  | 22 (17.2) | 27 (21.1) | 79 (61.7) |  |
Dichorionic | 30.2 ± 11.1 |  | 36 (19.7) | 46 (25.1) | 101 (55.2) |  |
Season of sampling | Â | 0.745 | Â | Â | Â | 0.862 |
Summer/autumn | 31.3 ± 11.1 |  | 34 (18.1) | 46 (24.5) | 108 (57.5) |  |
Winter/spring | 30.8 ± 11.3 |  | 24 (19.5) | 27 (22.0) | 72 (58.5) |  |