Table 3.

Effect of additional adjustment by potential confounding factors on the RR and 95% CI of invasive cervical cancer in relation to lifetime number of sexual partners or age at first intercourse in a subset of 5,383 cases and 9,500 controls who had complete information on all variables

Adjustment variablesRR (95% CI)
Lifetime number of sexual partners (≥2 vs 1)5-y decrease in age at first intercourse
Age + study2.21 (2.03-2.41)2.02 (1.89-2.15)
Age + study + lifetime number of sexual partners or age at first intercourse1.86 (1.65-2.10)1.78 (1.66-1.91)
As above +
    Number of full-term pregnancies1.91 (1.57-2.33)1.51 (1.36-1.67)
    Age at first full-term pregnancy1.93 (1.59-2.35)1.22 (0.95-1.55)
    Education2.00 (1.69-2.38)1.49 (1.35-1.63)
    Tobacco smoking1.72 (1.50-1.98)1.73 (1.60-1.87)
    Hormonal contraceptive use1.74 (1.53-1.99)1.82 (1.69-1.97)
    Condom use1.81 (1.59-2.06)1.74 (1.62-1.88)
    History of Pap smear1.65 (1.41-1.95)1.69 (1.55-1.85)
    Number of and age at first full-term pregnancy1.75 (1.21-2.53)1.18 (0.78-1.78)