Table 1

Characteristics of cases (active sperm <12×106/ml) and referents (active sperm ⩾12×106/ml) in the Montreal and CITES series

MontrealCITES
CasesReferentsCasesReferents
n%n%n%n%
Age (y):
 ⩽307837.518942.49052.320251.0
 31–357435.612427.85833.713032.8
 >355626.913329.82414.06416.2
All208100.0446100.0172100.0396100.0
Clinic year:
 1972–767636.216837.7
 1977–816531.013931.2
 1982–916932.913931.2175100.0399100.0
All210100.0446100.0175100.0399100.0
Possible lead exposure3717.68118.24425.111428.6
No previous pregnancy1-150 17684.231671.21-165 15588.631177.91-160
Partner ‘normal’10047.616236.31-160 10560.012431.11-165
  • 1-150 Information missing for 1 case and 2 referents in the Montreal study.

  • 1-160 p<0.01 cases v referents.

  • 1-165 p<0.001 cases v referents.