Table 4 Meta-regression results for effect of different metformin therapy strategy among subgroup of POCS women and healthy controls and study methodology
| Â | Regression coefficient (95% CI) | P value |
|---|---|---|
Comparison between PCOS and healthy controls | ||
 Women with PCOS, No treated with metformin vs. healthy controls | ||
  Non-RCTs~ | 0.10 (0.02, 0.17) | 0.006 |
  RCTs | –* | – |
 Women with PCOS, treated with metformin only before conception vs. healthy controls | ||
  Non-RCTs | 0.14 (0.07, 0.2) | 0.000 |
  RCTs | –* | – |
 Women with PCOS, treated with metformin before conception till the end of pregnancy vs. healthy controls | ||
  Non-RCTs | 0.035 (− 0.03, 0.1) | 0.324 |
  RCTs | –* | –* |
Comparison between PCOS population | ||
 Women with PCOS, treated with metformin only before conception vs. without metformin therapy | ||
  Non-RCTs | 0.08 (− 0.03, 0.2) | 0.390 |
  RCTs | –* | – |
 Women with PCOS, treated with metformin before conception till the end of pregnancy vs. without metformin therapy | ||
  Non-RCTs | − 0.05 (− 0.07, 0.04) | 0.602 |
  RCTs | –* | – |
 Women with PCOS, treated with metformin before conception till the end of pregnancy vs. only before conception | ||
  Non-RCTs | − 0.11 (− 0.24, 0.02) | 0.097 |
  RCTs | − 0.03 (− 0.25, 0.20) | 0.757 |