Table 4 Comparison of epidemiological studies for the association between years of fertility, age at menarche, and age of menopause and gastric cancer.

First author [reference]	Design	Study location	Cases/controls	Referent group (years)		Exposed group (years)	Risk ratio* (95% CI)
Years of fertility
Palli†27	Retrospective	Italy	339/515	<33		⩾40	0.6 (0.4 to 0.9)
La Vecchia†26	Retrospective	Italy	227/606	<32		⩾39	0.66 (0.4 to 1.1)
Inoue†,‡23	Retrospective	Japan	365/1825	⩽32		⩾39	0.80 (0.55 to 1.16)
Kaneko†24	Prospective	Japan	156/40 535	<31		>35	0.83 (0.54 to 1.26)
Frise†20	Retrospective	Canada	269/261	<27		>38	0.80 (0.49 to 1.31)
This study†	Prospective	China	120/35 944	<30		>36	0.60 (0.35 to 1.04)
Age at menarche
Palli27	Retrospective	Italy	339/515		<13	⩾15	1.0 (0.6 to 1.4)
La Vecchia26	Retrospective	Italy	228/608		<13	⩾15	0.77 (0.5 to 1.2)
Heuch21	Prospective	Norway	554/63 090		⩽12	⩾17	0.7 (0.5 to 1.1)
Inoue23	Retrospective	Japan	365/1825		⩽12	⩾15	1.15 (0.73 to 1.81)
Kaneko24	Prospective	Japan	156/40 535		<14	>15	0.86 (0.52 to 1.41)
Frise20	Retrospective	Canada	326/326		<13	⩾15	1.94 (1.21 to 3.10)
This study	Prospective	China	153/73 413		<14	>16	0.72 (0.42 to 1.22)
Age of menopause
Palli27	Retrospective	Italy	339/515	<45		⩾55	0.6 (0.3 to 1.0)
La Vecchia26	Retrospective	Italy	228/608	<45		⩾53	0.57 (0.3 to 1.1)
Heuch21	Prospective	Norway	315/22 151	⩽45		⩾54	0.9 (0.5 to 1.6)
Inoue23	Retrospective	Japan	365/1825	⩽44		⩾55	0.92 (0.44 to 1.90)
Kaneko24	Prospective	Japan	156/40 535	<47		>51	0.93 (0.60 to 1.44)
Frise‡20	Retrospective	Canada	326/326	<45		Pre‐menopausal	0.57 (0.29 to 1.12)
This study	Prospective	China	120/35 944	<46		>51	0.52 (0.30 to 0.91)

*Odds ratio for retrospective studies and hazard ratio for prospective studies.

^†Restricted to post‐menopausal women.

^‡Referent group and subsequent odds ratio inverted for consistent presentation.