From: Breastfeeding and the risk of childhood cancer: a systematic review and dose-response meta-analysis
 | No. of studies | No. of cases | OR (95%CI) | P value | I2 (%) | P value for heterogeneity | P in meta-regression |
---|---|---|---|---|---|---|---|
Cancer type | Â | Â | Â | Â | Â | Â | 0.396 |
 Ependymoma (C.1) | 4 | 408 | 1.02 (0.65 ~ 1.60) | 0.931 | 22.3 | 0.277 |  |
 Astrocytoma (C.2) | 4 | 475 | 0.91 (0.71 ~ 1.15) | 0.411 | 0.0 | 0.589 |  |
 Medulloblastoma (C.3) | 2 | 148 | 0.89 (0.42 ~ 1.92) | 0.770 | 53.4 | 0.143 |  |
 Others (C.4) | 3 | 446 | 1.13 (0.83 ~ 1.55) | 0.446 | 22.1 | 0.274 |  |
Year of publication | Â | Â | Â | Â | Â | Â | 0.665 |
 In and before 2005 (C.5) | 4 | 640 | 0.95 (0.69 ~ 1.30) | 0.751 | 37.8 | 0.186 |  |
 After 2005 (C.6) | 3 | 1019 | 0.94 (0.80 ~ 1.10) | 0.431 | 0.0 | 0.458 |  |
Geographic location | Â | Â | Â | Â | Â | Â | 0.296 |
 North America (C.7) | 2 | 310 | 0.74 (0.55 ~ 1.01) | 0.055 | 0.0 | 0.364 |  |
 Europe (C.8) | 4 | 1071 | 1.03 (0.90 ~ 1.19) | 0.639 | 0.0 | 0.636 |  |
 Oceania (C.9) | 1 | 278 | 0.81 (0.47 ~ 1.39) | 0.443 | NA | NA |  |
Study quality score | Â | Â | Â | Â | Â | Â | 0.847 |
 ≤ 7 (C.10) | 5 | 926 | 0.92 (0.72 ~ 1.16) | 0.472 | 35.6 | 0.184 |  |
 > 7 (C.11) | 2 | 733 | 0.98 (0.82 ~ 1.17) | 0.825 | 0.0 | 0.479 |  |
Sample size | Â | Â | Â | Â | Â | Â | 0.179 |
 ≤ 1000 (C.12) | 4 | 631 | 0.81 (0.62 ~ 1.06) | 0.121 | 4.7 | 0.369 |  |
 > 1000 (C.13) | 3 | 1028 | 1.02 (0.89 ~ 1.17) | 0.772 | 0.0 | 0.560 |  |
Definition of reference category | Â | Â | Â | Â | Â | Â | 0.665 |
 Never breastfeeding (C.14) | 3 | 1019 | 0.94 (0.80 ~ 1.10) | 0.431 | 0.0 | 0.458 |  |
 Occasional breastfeeding (C.15) | 4 | 640 | 0.95 (0.69 ~ 1.30) | 0.751 | 37.8 | 0.186 | 0.207 |
  ≤ 2 months (C.16) | 3 | 602 | 1.08 (0.88 ~ 1.32) | 0.482 | 0.0 | 0.489 |  |
  ≤ 6 months (C.17) | 1 | 38 | 0.57 (0.30 ~ 1.09) | 0.088 | NA | NA |  |