Table 4.

Relative risk (ORs with 95% CI) of cervical atypia (cytological SIL and/or CIN grade 1 or worse, CIN1+) stratified by the interval between menarche and age at FSI or between menarche and the age at start of OC use in young adult women followed up for 4 years

Frequency and relative risk of cytological atypia: SIL or CIN1 in the different categories by interval from menarche
Variable	Category 1			Category 2
	Menarche to FSI <3 years SIL/CIN1+			Menarche to start of OCs ≥3 years SIL/CIN1+
	n/N	OR (95% CI)		n/N	OR (95% CI)
Lag between FSI and menarche
<3 years.	53/301	NA		23/110	0.9 (0.5 to 1.4)	0.9 (0.8 to 1.0)
≥3 years	NA	NA		132/565	1	*Interval (cont.)
Lag between start of OCs and menarche
<3 years.	30/191	0.7 (0.4 to 1.3)	0.9 (0.9 to 1.0)	NA	NA
≥3 years	23/110	1	*Interval (cont.)	155/675	NA

CIN, cervical intraepithelial neoplasia; FSI, first sexual intercourse; OC, oral contraceptive; SIL, squamous intraepithelial lesion.