Table 1 Subgroup analyses of different outcome indicators
From: Association between maternal breastfeeding and risk of systemic neoplasms of offspring
Outcome indicators | Number of studies | Sample size | OR, 95%CI | P for OR | I2 | I2 for P |
|---|---|---|---|---|---|---|
Childhood cancer (Ever vs. Never) | 35 | 468,727 | 0.83 [0.75, 0.92] | 0.0003 | 82% | P < 0.00001 |
Duration | ||||||
 Duration ≥1 month vs. < 1 month | 11 | 25,609 | 0.75 [0.63, 0.89] | 0.001 | 80% | P < 0.00001 |
 Duration ≥6 months vs. < 6 months | 32 | 41,813 | 0.82 [0.74, 0.90] | 0.0001 | 62% | P < 0.00001 |
 Duration ≥12 months vs. < 12 months | 13 | 8490 | 0.82 [0.65, 1.04] | 0.09 | 68% | P < 0.0002 |
 Exclusive ≥6 months vs. 6 months | 4 | 3243 | 0.98 [0.75, 1.28] | 0.88 | 45% | 0.14 |
Country developed vs. developing | 31 | 465,845 | 0.89 [0.83, 0.95] | 0.001 | 55% | 0.0002 |
Gender female vs. male | 29 | 467,962 | 0.96 [0.92, 1.01] | 0.13 | 0% | 0.71 |
High quality studies | 24 | 33,407 | 0.78 [0.67, 0.91] | 0.002 | 88% | P < 0.00001 |
The mode of breastfeeding | ||||||
 Exclusive vs. Mixed and Formula | 8 | 11,199 | 0.82 [0.66, 1.02] | 0.08 | 82% | P < 0.00001 |
 Mixed vs. Formula and Exclusive | 10 | 28,166 | 0.95 [0.91, 1.00] | 0.07 | 41% | 0.8 |
 Formula vs. Mixed and Exclusive | 8 | 26,165 | 1.38 [1.00, 1.92] | 0.05 | 95% | P < 0.00001 |
Exclusive vs. Mixed | 7 | 8865 | 0.99 [0.90, 1.08] | 0.82 | 0% | 0.99 |
 Exclusive vs. Mixed 0–6 months | 3 | 3234 | 0.96 [0.80, 1.15] | 0.68 | 45% | 0.14 |
 Exclusive vs. Mixed 6–12 months | 1 | 251 | 1.08 [0.65, 1.81] | 0.76 | NA | NA |
 Exclusive vs. Mixed > 12 months | 1 | 142 | 0.78 [0.37, 1.64] | 0.52 | NA | NA |
Exclusive vs. Formula | 5 | 5764 | 0.54 [0.23, 1.25] | 0.15 | 96% | P < 0.00001 |
Mixed vs. Formula | 7 | 22,361 | 0.75 [0.53, 1.07] | 0.11 | 95% | P < 0.00001 |
 Mixed vs. Formula < 1 month | 1 | 7891 | 1.02 [0.91, 1.01] | 0.75 | NA | NA |
 Mixed vs. Formula ≥1 month | 1 | 7650 | 1.01 [0.91, 1.14] | 0.84 | NA | NA |
Type of cancer | ||||||
 Hematologic malignancies | 24 | 445,481 | 0.82 [0.71,0.94] | 0.005 | 85% | P < 0.00001 |
 Leukemia | 19 | 437,644 | 0.89 [0.82, 0.97] | 0.009 | 49% | 0.008 |
  ALL | 19 | 435,166 | 0.90 [0.85, 0.95] | 0.0003 | 55% | 0.002 |
  AML | 3 | 8761 | 0.79 [0.66, 0.94] | 0.009 | 62% | 0.07 |
  ANLL | 3 | 694 | 1.10 [0.68, 1.80] | 0.69 | 0% | 0.95 |
 Lymphoma | 5 | 10,443 | 0.93 [0.79, 1.09] | 0.36 | 0% | 0.72 |
  HL | 4 | 8270 | 0.89 [0.68, 1.15] | 0.36 | 0% | 0.63 |
  NHL | 5 | 9318 | 0.96 [0.79, 1.17] | 0.67 | 0% | 0.78 |
 Nervous system | 9 | 19,923 | 0.72 [0.54, 0.96] | 0.02 | 89% | P < 0.00001 |
 Skeletal system | 1 | 636 | 0.85 [0.62, 1.16] | 0.30 | NA | NA |
 Urinary system | 1 | 904 | 0.69 [0.51, 0.92] | 0.01 | NA | NA |
 Reproductive system | 1 | 744 | 1.11 [0.73, 1.67] | 0.63 | NA | NA |
 Sensory system | 1 | 337 | 0.77 [0.39, 1.50] | 0.44 | NA | NA |
Three largest studies | 3 | 21,769 | 0.90 [0.79, 1.04] | 0.16 | 84% | 0.002 |