Does parity affect mortality among parous women?

To find out whether there is an association between parity and mortality.

Prospective cohort study.

Northern Finland, 1966-2001.

12,055 women in the two northernmost provinces of Finland were followed up from pregnancy in 1966-2001, the coverage percentage being 96%. The data on age, smoking, body mass index, socioeconomic position, age at menarche and age at first birth were collected during pregnancy, and data on deaths were obtained from the National Cause of Death Statistics, maintained by Statistics Finland. The Cox proportional hazard model was used to estimate relative mortality between parity groups.

Total mortality was lowest among the women with 2-4 children (reference group). High parity was associated with an up to twofold risk of mortality from vascular complications, but after adjustment for all background factors, this significance disappeared. Mortality from haemorrhagic stroke was fourfold higher among the women with > or = 10 births compared with those of the reference group. No differences in cerebral infarction or total cancer mortality were seen between the groups. Primiparity was associated with increased mortality from accidental death (relative risk 2.6, 95% confidence interval 1.6 to 4.4).

High parity was associated with an increased risk of mortality from vascular complications, especially haemorrhagic stroke, and primiparity with an increased risk of accidental death.