Higher parity associated with higher risk of death from gastric cancer

Table 1 Demographic characteristics of the study cohort (mean ± SD) n (%)

	Parity			P-value
	1 (n = 157 207)	2-3 (n = 1 000 977)	4+ (n =134 278)
Age at recruitment (1st birth)	26.38 ± 4.43	24.26 ± 3.22	22.44 ± 2.95	< 0.001
Marital status
Married	146 022 (92.89)	984 049 (98.31)	130 544 (97.22)	< 0.001
Not married	11 185 (7.11)	16 928 (1.69)	3734 (2.78)
Years of schooling
≤ 9	72 090 (45.86 )	544 098 (54.36)	106 330 (79.19)	< 0.001
> 9	85 117 (54.14)	456 879 (45.64)	27 948 (20.81)
Birth place
Hospital/clinic	153 167 (97.43)	970 422 (96.95)	122 336 (91.11)	< 0.001
Home/other	4040 (2.57)	30 555 (3.05)	11 942 (8.89)

Table 2 Association between parity and hazard ratio of death from gastric cancer over a 31-year follow-up period

Parity	No. of subjects	Follow-up person-years	No. of gastric cancer (per 100 000)	Age-adjusted HR (95% CI)	Multivariate-adjusted HR1 (95% CI)
1	157 207	4 020 271.75	128 (3.18)	1.00	1.00
2-3	1 000 977	26 036 992.42	848 (3.25)	1.23 (1.01-1.49)	1.24 (1.02-1.50)
4+	134 278	3 629 563.83	114 (3.14)	1.33 (1.02-1.73)	1.32 (1.01-1.72)
				P = 0.030 for linear trend	P = 0.035 for linear trend

¹Adjusted for age, marital status, years of schooling, and birth place. HR: Hazard ratio; CI: Confidence interval.