Table 1 Preregistered and exploratory Cox proportional hazards models

Target variable	N	Deaths	z-score	p	HR^† (95% CI)
Primary preregistered models
Age first birth	182,034	5199	−3.406	0.0007	0.9879 (0.9810–0.9949)
Age first OC use	209,403	5264	3.668	0.0002	1.0122 (1.0057–1.0188)
Ever used OC	268,088	7700	−3.129	0.0018	0.9188 (0.8714–0.9689)
Secondary preregistered models
Age at menarche	260,524	7453	−5.043	4.57e−07	0.9649 (0.9517–0.9784)
Age at menopause	152,508	5387	−5.707	1.15E−08	0.9858 (0.9809–0.9906)
Combined exploratory model^††
Age first OC use	190,394	4556	3.159	0.0016	1.0117 (1.0044–1.0190)
Age first sex			−0.241	0.81 NS	0.9992 (0.9927–1.0057)
Age at menarche			−4.591	4.41e−06	0.9589 (0.9418–0.9762)
Total parity			−2.580	0.0099	0.9663 (0.9414–0.9981)

^†All hazard ratios are given as a per year increase in predictor variable, such the increase in mortality hazard associated with a 1-year-later onset of menarche, except for total parity, which is per child, and the HR associated with using oral contraceptives (Ever Used OC).
^††Z-scores and p values are from a single model with N = 190,394 and 4556 deaths; parity is for age 50 and over. p values assessed at the preregistered cut-off of 0.01, not 0.05.

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