Table 1. Observed (Obs) and expected (Exp) number of cervical intraepithelial neoplasia (CIN3) and cervical cancer (CC) cases and standardised incidence ratios (SIR=Obs/Exp), with 95% confidence intervals (95% CI), among women with at least five children.

	CIN3				CC
Variable	Obs	Exp	SIR	95% CI	Obs	Exp	SIR	95% CI
Parity
5	92	70	1.32	1.06–1.62	111	98	1.13	0.93–1.36
6	52	34	1.55	1.16–2.03	65	56	1.17	0.90–1.49
7	18	12	1.48	0.88–2.34	24	18	1.32	0.84–1.96
8+	16	15	1.08	0.62–1.76	20	23	0.87	0.53–1.34
Age at first birth (years)
<20	51	29	1.74	1.30–2.29	42	23	1.82	1.31–2.46
20–24	93	71	1.31	1.06–1.61	107	94	1.14	0.94–1.38
25–29	27	25	1.09	0.72–1.58	54	59	0.92	0.69–1.20
30+	7	5	1.33	0.53–2.73	17	20	0.87	0.51–1.39
Birth interval (years)
<2.0	68	42	1.62	1.26–2.05	68	55	1.24	0.97–1.58
2.0–3.0	72	50	1.45	1.13–1.82	78	79	0.99	0.78–1.24
3.0+	38	38	0.99	0.70–1.36	74	62	1.20	0.94–1.50
Age at follow up (years)
<40	38	25	1.51	1.07–2.08	17	7	2.36	1.37–3.77
40–49	62	44	1.42	1.09–1.82	40	29	1.36	0.97–1.86
50–64	59	48	1.23	0.94–1.5	106	100	1.07	0.87–1.29
65+	19	14	1.41	0.85–2.20	57	59	0.96	0.73–1.25