Table 2. Odds ratios (ORs) and 95% confidence intervals (CIs) for adenocarcinomas and squamous cell carcinomas of the cervix in relation to reproductive factors.

	Adenocarcinoma			Squamous cell carcinoma			Squamous vs adenocarcinoma
	Cases/controls	ORa	95% CI	Cases/controls	ORb	95% CI	Squamous/adeno cases	ORc	95% CI
Ever given birth
Never	21/150	1.00		60/150	1.00		60/21	1.00
Ever	159/773	1.24	0.72–2.14	331/773	1.26	0.85–1.86	331/159	1.09	0.58–2.04
Total number of live births
0	21/150	1.00		60/150	1.00		60/21	1.00
1	38/176	1.27	0.69–2.34	62/176	0.88	0.55–1.40	62/38	0.73	0.36–1.49
2	65/377	1.14	0.63–2.05	145/377	1.41	0.92–2.17	145/65	1.33	0.67–2.63
3+	56/220	1.44	0.76–2.73	124/220	1.86	1.16–2.99	124/56	1.47	0.70–3.11
Trend			P=0.3			P=0.001			P=0.1
Time since last birth
Never	21/150	1.00		60/150	1.00		60/21	1.00
⩽10 years	77/468	1.13	0.65–1.99	219/468	1.30	0.88–1.94	219/77	1.24	0.65–2.37
10+ years	82/305	1.63	0.86–3.07	112/305	1.07	0.66–1.73	112/82	0.66	0.32–1.40
Heterogeneity between groups within parous women			P=0.2			P=0.3			P=0.03
Age at first birth
Never	21/150	1.00		60/150	1.00		60/21	1.00
25+ years	36/272	0.92	0.49–1.70	70/272	0.94	0.60–1.47	70/36	1.07	0.52–2.18
20–24 years	63/322	1.40	0.77–2.55	108/322	1.23	0.79–1.91	108/63	1.04	0.51–2.11
15–19 years	60/179	1.71	0.89–3.29	153/179	2.01	1.26–3.21	153/60	1.16	0.57–2.38
Trend within parous women			P=0.03			P=0.002			P=0.7
Number of interrupted pregnancies
0	126/647	1.00		239/647	1.00		239/126	1.00
1+	54/276	0.91	0.63–1.31	152/276	1.16	0.88–1.54	152/54	1.36	0.89–2.08

OR_a, odds ratio for adenocarcinoma vs controls; OR_b, odds ratio for squamous cell carcinoma vs controls; OR_c, odds ratio for squamous cell carcinoma vs adenocarcinoma cases; all adjusted for age, region, total number of sexual partners, age at first intercourse, smoking, duration of oral contraceptive use, number of negative screening results and education.