Table 2.

Survival analyses of the associations between age at menarche, parity and hysterectomy in the NSHD (N = 1184).

Reproductive characteristic	Unadjusted hazard ratio for hysterectomy (95% CI)	Hazard ratio for hysterectomy (95% CI) adjusted for other reproductive characteristic	Fully adjusteda hazard ratio for hysterectomy (95% CI)
Age at menarche
Per 1 year increase	0.85 (0.77–0.94)	0.85 (0.77–0.94)	0.85 (0.77–0.95)
p-Value	0.002	0.001	0.003
Parity (No. of children)
0	1.00	1.00	1.00
1	1.94 (1.23–3.06)	1.98 (1.25–3.13)	1.89 (1.20–3.00)
2	1.62 (1.07–2.46)	1.66 (1.10–2.52)	1.57 (1.03–2.40)
≥3	2.84 (1.84–4.39)	2.91 (1.88–4.48)	2.79 (1.80–4.34)
p-Value	<0.001	<0.001	<0.001

^aAdjusted for other reproductive characteristic, father’s occupational class, educational level attained and body mass index.