Subgroup analysis of the association between maternal vitamin D deficiency and SGA
| Stratification group | N | p Value for OR | OR (95% CI) | Heterogeneity test | |
| I2(%) | p Value | ||||
| Study quality (NOS) | |||||
| High | 915 17 18 24 25 28–31 | <0.001 | 1.555 (1.239 to 1.951) | 37.6 | 0.118 |
| Low | 44 16 26 27 | 0.440 | 1.441 (0.570 to 3.641) | 95.2 | <0.001 |
| Gestation of blood sampling | |||||
| first trimester | 515 27–30 | 0.104 | 1.286 (0.950 to 1.741) | 65.9 | 0.020 |
| second trimester | 516 18 24 25 31 | 0.011 | 1.577 (1.110 to 2.240) | 51.1 | 0.085 |
| mixed (first or second or third) | 34 17 26 | 0.432 | 90.6 | <0.001 | |
| Cut-off values | |||||
| <10 ng/mL | 224 31 | 0.001 | 2.219 (1.480 to 3.325) | 0 | 0.446 |
| <15 ng/mL | 215 16 | 0.029 | 1.532 (1.046 to 2.246) | 73.2 | 0.054 |
| <20 ng/mL | 94 17 18 25–30 | 0.172 | 1.448 (0.851 to 2.465) | 88.2 | <0.001 |
| Sample size | |||||
| >1000 | 104 15 16 24 25 27–31 | 0.003 | 1.760 (1.217 to 2.544) | 86.8 | <0.001 |
| >1000 | 317 18 26 | 0.946 | 0.975 (0.476 to 1.999) | 45.5 | 0.160 |
| Adjust for critical confounders | |||||
| yes | 104 15 17 18 24 26 29–31 | 0.018 | 1.681 (1.094 to 2.584) | 86.3 | <0.001 |
| no | 316 25 28 | 0.180 | 1.219 (0.912 to 1.629) | 22.3 | 0.276 |
| Measurement of vitamin D | |||||
| LC-MS/MS | 616 18 26 27 29 31 | 0.204 | 1.195 (0.908 to 1.573) | 59.5 | 0.031 |
| Others | 74 15 17 24 25 28 29 | 0.006 | 2.224 (1.263 to 3.918) | 85.8 | <0.001 |