Table 2 Results of heterogeneity and publication bias estimation and subgroup meta-analysis for various study population and metformin treatment among women with PCOS and without PCOS
|  | Sample size of participants | Chi square (df) | P value | Begg’s test | Pooled overall prevalence (95% CI) |
|---|---|---|---|---|---|
Gestational diabetes in first trimester of pregnancy | |||||
 PCOS | 337 | 4.25 (5) | 0.510 | 0.452 | 0.16 (0.12, 0.19) |
  Without metformin therapy | 257 | − (1) | – | 0.317 | 0.15 (0.10, 0.19) |
  Metformin therapy just before conception | 44 | − (1) | – | 1 | 0.27 (0.14, 0.40) |
  Metformin therapy before conception till end of pregnancy | 36 | − (1) | – | 0.317 | 0.13 (0.02, 0.25) |
 Non-PCOS | 0 | – | – | – | – |
Gestational diabetes in second trimester of pregnancy | |||||
 PCOS | 5156 | 1123 (58) | 0.001 | 0.789 | 0.19 (0.16, 0.22) |
  Without metformin therapy | 3008 | 772 (28) | 0.001 | 0.341 | 0.20 (0.15, 0.25) |
  Metformin therapy just before conception | 1232 | 165 (15) | 0.001 | 0.786 | 0.23 (0.16, 0.30) |
  Metformin therapy before conception till end of pregnancy | 916 | 61 (13) | 0.001 | 0.555 | 0.11 (0.07, 0.16) |
 Non-PCOS | 12,059 | 433 (22) | 0.001 | 0.321 | 0.07 (0.06, 0.09) |
Gestational diabetes in third trimester of pregnancy | |||||
 PCOS | 575 | 11 (5) | 0.001 | 0.573 | 0.16 (0.08, 0.23) |
  Without metformin therapy | 495 | − (1) | – | 1 | 0.12 (0.09, 0.15) |
  Metformin therapy just before conception | 44 | − (1) | – | 1 | 0.09 (0.01, 0.18) |
  Metformin therapy before conception till end of pregnancy | 36 | − (1) | – | 1 | 0.22 (0.09, 0.36) |
 Non-PCOS | 8151 | − (1) | – | 0.317 | 0.04 (0.03, 0.04) |