Table 3. RRs and 95% CIs for squamous cell and adenocarcinomas of the oesophagus in relation to reproductive factors.

	Oesophagus, squamous cell carcinoma		Oesophagus, adenocarcinoma
	n Cases	RR, 95% CI	n Cases	RR, 95% CI	Test for difference, squamous cell and adenocarcinoma (P)
Menarche and menopause
Age at menarche
<13 Years	184	0.95, 0.78–1.15	178	1.29, 1.04–1.60	0.003
13–14 Years	259	Ref	158	Ref
15+ Years	119	1.04, 0.84–1.30	53	0.80, 0.59–1.10
Trend per year older		1.02, 0.97–1.09		0.89, 0.82–0.95
	Ptrend=0.4		Ptrend=0.001
Menopausal status
Pre/perimenopausal
Postmenopausal	31	Ref	20	Ref	0.4
	258	1.65, 1.08–2.53	183	1.18, 1.69–2.04
	Pheterogeneity=0.02		Pheterogeneity=0.5
Age at menopause
50+ Years	101	Ref	96	Ref	0.04
45–49 Years	102	1.69, 1.28–2.24	55	1.12, 0.80–1.57
<45 Years	42	1.65, 1.14–2.39	19	0.89, 0.54–1.47
Trend per 5 years younger		1.32, 1.11–1.56		0.98, 0.78–1.23
	Ptrend=0.002		Ptrend=0.9
Type of menopause
Natural	253	Ref	176	Ref	0.4
Bilateral oophorectomy	5	0.59, 0.24–1.14	7	1.13, 0.52–2.46
	Pheterogeneity=0.2		Pheterogeneity=0.8
Childbearing
Parity
Nulliparous	97	1.60, 1.28–2.00	36	0.86, 0.61–1.21	0.003
Parous	480	Ref	362	Ref
	Pheterogeneity<0.0001		Pheterogeneity=0.4
Number of full-term pregnanciesa
1	78	0.91, 0.69–1.22	55	0.86, 0.61–1.19	0.3
2	206	Ref	168	Ref
3+	196	1.11, 0.91–1.37	139	0.84, 0.66–1.07
Trend per birth		1.08, 0.97–1.20		0.95, 0.84–1.08
	Ptrend=0.2		Ptrend=0.5
Age at first birtha
<20 Years	59	0.87, 0.65–1.16	40	0.69, 0.48–0.97	0.6
20–24 Years	224	Ref	194	Ref
25–29 Years	135	1.12, 0.90–1.40	88	0.84, 0.65–1.09
30+ Years	45	1.11, 0.80–1.54	31	0.85, 0.57–1.25
Trend per 5 years older		1.10, 0.96–1.35		1.00, 0.86–1.17
	Ptrend=0.2		Ptrend=0.9
Breastfeedinga
Never	120	Ref	105	Ref	0.1
Ever	256	0.97, 0.77–1.22	168	0.75, 0.58–0.97
	Pheterogeneity=0.8		Pheterogeneity=0.03

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.