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Table 2 Association of significant reproductive factors and lung cancer risk, stratified by subgroups (highest vs. lowest category)

From: Reproductive factors and lung cancer risk: a comprehensive systematic review and meta-analysis

Reproductive factorsa n OR (95% CI)b Case-Control Cohort
n OR (95% CI)b n OR (95% CI)b
Parity (highest vs. lowest)
 Overall lung cancer 24 0.83 (0.72, 0.96) 15 0.82 (0.68, 0.98) 9 0.85 (0.68, 1.05)
  Asian 12 0.70 (0.58, 0.86) 7 0.81 (0.65, 1.01) 5 0.58 (0.44, 0.75)
  Caucasian 8 1.03 (0.85, 1.25) 5 0.93 (0.60, 1.43) 3 1.12 (0.96, 1.31)
 Adenocarcinoma 10 0.83 (0.63, 1.09) 5 1.00 (0.82, 1.22) 5 0.71 (0.43, 1.16)
  Asian 5 0.72 (0.37, 1.39) 2 1.22 (0.86, 1.73) 3 0.45 (0.28, 0.71)
  Caucasian 4 0.93 (0.76, 1.13) 2 0.74 (0.44, 1.24) 2 0.97 (0.78, 1.20)
 Non-small cell lung cancer 10 0.84 (0.63, 1.11) 5 0.81 (0.51, 1.29) 5 0.85 (0.57, 1.27)
  Asian 4 0.82 (0.33, 2.07) 2 1.22 (0.86, 1.73) 2 0.39 (0.18, 0.84)
  Caucasian 4 0.94 (0.69, 1.29) 2 0.74 (0.44, 1.24) 2 0.97 (0.78, 1.20)
 Never Smokers 11 0.71 (0.54, 0.93) 5 0.65 (0.52, 0.81) 6 0.80 (0.51, 1.28)
  Asian 7 0.65 (0.54, 0.78)     
  Caucasian 2 0.99 (0.25, 3.85)     
 Ever Smokers 8 0.78 (0.59, 1.04) 4 0.56 (0.41, 0.75) 4 1.01 (0.76, 1.34)
  Asian 4 0.54 (0.40, 0.75)     
  Caucasian 2 1.14 (0.92, 1.40)     
Parity (highest vs. nulliparous)
 Overall lung cancer 16 0.77 (0.62, 0.95) 10 0.79 (0.62, 1.00) 6 0.72 (0.49,1.06)
  Asian 5 0.56 (0.47, 0.67) 1 0.61 (0.43, 0.87) 4 0.55 (0.45, 0.66)
  Caucasian 8 0.96 (0.73, 1.26) 6 0.83 (0.58, 1.18) 2 1.22 (0.97, 1.52)
 Adenocarcinoma 8 0.71 (0.49, 1.01) 4 0.83 (0.64, 1.08) 4 0.66 (0.31, 1.41)
  Asian 3 0.45 (0.28, 0.71)    3 0.45 (0.28, 0.71)
  Caucasian 4 0.84 (0.52, 1.35) 3 0.66 (0.45, 0.98) 1 1.41 (0.90, 2.20)
Age at first birth
 Overall lung cancer 19 0.85 (0.74, 0.98) 12 0.77 (0.61, 0.97) 7 0.94 (0.81, 1.08)
  Asian 9 0.90 (0.66, 1.22)     
  Caucasian 6 0.75 (0.65, 0.88)     
 Adenocarcinoma 10 0.84 (0.74, 0.95) 6 0.85 (0.72, 1.00) 4 0.82 (0.67, 1.01)
  Asian 3 0.62 (0.47, 0.83)     
  Caucasian 5 0.82 (0.68, 0.97)     
Non-natural menopause
 Overall lung cancer 11 1.52 (1.25, 1.86) 6 1.83 (1.50, 2.22) 5 1.17 (1.00, 1.37)
  Asian 4 1.36 (1.07, 1.72)     
  Caucasian 5 1.67 (1.12, 2.49)     
 Adenocarcinoma 6 1.41 (1.18, 1.69) 5 1.64 (1.25, 2.14) 1 1.24 (0.97, 1.59)
  Caucasian 5 1.44 (1.19, 1.74)     
Menstrual cycle length
 Overall lung cancer 7 0.79 (0.65, 0.96) 7 0.79 (0.65, 0.96)   
  Asian 3 0.64 (0.49, 0.85)     
  Caucasian 4 0.98 (0.74, 1.28)     
 Adenocarcinoma 4 0.79 (0.55, 1.14) 4 0.79 (0.55, 1.14)   
  Caucasian 3 0.79 (0.51, 1.21)     
  1. aSubgroup analyses were conducted if there were at least four studies published for that reproductive variable
  2. bAdjusted odds ratio (OR) and 95% confidence interval (CI). Highest non-reference category as compared to the lowest reference group