Table 1. Characteristics of study participants.

Variable	Category	N	Age at natural menopause
			Mean	SD	P a	P b
Education					<0.001
	non	643	49.39	4.04
	Elementary	725	49.42	3.84
	Middle school	1000	49.12	3.49
	High school	757	49.71	3.42
	High profession/College+	407	50.48	3.32
Occupation					<0.001	<0.001
	Professional	937	50.07	3.40
	Clerical	642	49.61	3.52
	Manual workers	1952	49.22	3.77
Number of live birth						<0.001
	0	139	48.63	3.97
	1	752	48.93	3.47
	2	1261	49.90	3.35
	3	772	49.66	4.09
	4+	609	49.43	3.71
Ever take oral contraceptives					<0.001
	No	869	49.79	3.67
	Yes	278	50.64	3.47
Age at menarche (years)					0.902	0.7179
	≤12	237	49.62	4.00
	13	588	49.62	3.38
	14	611	49.59	3.52
	15	733	49.47	3.75
	16	638	49.48	3.30
	17	398	49.46	3.94
	≥18	326	49.32	4.21
Disease					<0.001	0.9861
	Healthy controls	1308	49.20	3.77
	Breast cancer	850	49.86	3.63
	Endometrial cancer	427	50.42	3.41
	Colorectal cancer	322	49.20	3.46
	Upper GI cancer	160	49.0	3.76
	Type 2 diabetes	466	49.31	3.46

^a P for ANOVA.

^b adjusting for Education.