Table 2. RRs and 95% CIs for incident cancers of the oesophagus and stomach in relation to reproductive factors.

	Oesophagus		Stomach
	n Cases	RR, 95% CI	n Cases	RR, 95% CI
Menarche and menopause
Age at menarche
<13 Years	444	1.11, 0.97–1.26	418	1.00, 0.88–1.14
13–14 Years	501	Ref	505	Ref
15+ Years	208	0.96, 0.82–1.13	243	1.10, 0.95–1.29
Trend per year older		0.96, 0.93–1.00		1.02, 0.98–1.06
	Ptrend=0.1		Ptrend=0.3
Menopausal status
Pre/perimenopausal	59	Ref	53	Ref
Postmenopausal	539	1.46, 1.07–2.00	526	1.59, 1.15–2.20
	Pheterogeneity=0.01		Pheterogeneity=0.004
Age at menopause
50+ Years	247	Ref	239	Ref
45–49 Years	180	1.32, 1.09–1.61	160	1.26, 1.03–1.54
<45 Years	78	1.34, 1.03–1.74	76	1.35, 1.04–1.76
Trend per 5 years younger		1.18, 1.05–1.34		1.18, 1.04–1.34
	Ptrend=0.01		Ptrend=0.01
Type of menopause
Natural	521	Ref	503	Ref
Bilateral oophorectomy	18	0.97, 0.60–1.57	23	1.22, 0.79–1.88
	Pheterogeneity=0.9		Pheterogeneity=0.4
Childbearing
Parity
Nulliparous	163	1.31, 1.11–1.55	125	1.01, 0.84–1.22
Parous	1021	Ref	1067	Ref
	Pheterogeneity=0.002		Pheterogeneity=0.9
Number of full-term pregnanciesa
1	164	0.94, 0.77–1.14	201	1.22, 1.02–1.47
2	445	Ref	425	Ref
3+	412	1.00, 0.87–1.15	441	1.03, 0.90–1.19
Trend per birth		1.02, 0.94–1.09		0.97, 0.90–1.04
	Ptrend=0.7		Ptrend=0.3
Age at first birtha
<20 Years	124	0.81, 0.66–0.99	156	1.01, 0.84–1.21
20–24 Years	511	Ref	515	Ref
25–29 Years	268	0.97, 0.83–1.13	261	0.98, 0.84–1.14
30+ Years	87	0.92, 0.73–1.17	97	1.09, 0.87–1.36
Trend per 5 y older		1.02, 0.94–1.12		1.02, 0.93–1.14
	Ptrend=0.6		Ptrend=0.7
Breastfeedinga
Never	260	Ref	243	Ref
Ever	521	0.89, 0.76–1.04	529	1.03, 0.88–1.12
	Pheterogeneity=0.2		Pheterogeneity=0.7

Abbreviations: CI=confidence intervals; ref=reference; RRs=relative risks.

RRs stratified by age, region and socioeconomic status and adjusted for body mass index, smoking, alcohol, strenuous exercise, use of oral contraceptives and, as appropriate, for all other reproductive factors and for use of hormone therapy for the menopause (HT).

Analyses of all menopausal factors restricted to never HT users; analyses of age at menopause restricted to women with natural menopause.

^aRestricted to parous women.