Table II.

Core covariates and their association with age at menopause of participants

	Crude HR, 95%CI	p-value
Birth weight	1.00, 1.00-1.00	0.53
BMIa	1.01, 0.99-1.03	0.55
Underweight	0.88, 0.70-1.13	0.32
Normal	reference
Overweight	1.09, 0.90-1.32	0.36
Obese	1.06, 0.76-1.47	0.74
Age at menarche	0.97, 0.92-1.01	0.15
8-11 years	1.15, 0.96-1.38	0.13
12-14	reference
15 or more	0.94, 0.77-1.16	0.56
Regular menstrual periodsa
Yes	reference
No	0.92, 0.78-1.09	0.35
Cycle length (days)a	0.96, 0.94-0.98	<0.001
20 or less	2.09, 1.04-4.21	0.04
21-35	reference
36 or more	0.47, 0.06-3.36	0.45
Ever used OC	0.89, 0.69-1.15	0.37
Age 1st used OC	0.95, 0.93-0.98	<0.001
Ever seen a doctor for possible infertility	1.19, 1.00-1.41	0.05
Age at 1st pregnancy	0.98, 0.97-0.99	<0.001
Parity
1	1.04, 0.90-1.20	0.62
2 or more	reference
Ever had ART treatment	1.37, 1.03-1.83	0.03
Active smoking
Current	1.45, 1.20-1.86	<0.001
Previous	1.22, 1.02-1.46	0.03
Never	reference
Age started smoking	0.95, 0.92-0.99	0.01
Pack years	1.02, 1.01-1.03	<0.001
Heavy smoker	1.59, 1.13-2.25	0.01
Moderate smoker	1.47, 1.15-1.87	0.02
Light smoker	1.20, 1.00-1.45	0.05
Non-smoker	reference
Passive smoking
Participant’s father smoker	1.12, 0.96-1.31	0.15
Participant’s partner smoker	1.14, 0.98-1.32	0.09

^ainformation assessed at baseline time point