Parity, age at first birth, and risk of death from chronic renal failure: a cohort study of parous women in Taiwan.

BACKGROUND

This study was undertaken to examine whether there is an association between parity and age at first birth and risk of death from chronic renal failure (CRF).

STUDY DESIGN

Prospective cohort study.

SETTING AND PARTICIPANTS

The study cohort consisted of 1 292 462 women who had a first and singleton childbirth between January 1, 1978 and December 31, 1987. We tracked each woman from the time of their first childbirth to December 31, 2009, and their vital status was ascertained by linking records with the computerized mortality database.

PREDICTORS

Parity and age at first birth.

OUTCOME

Death of chronic renal failure (CRF).

RESULTS

There were 225 CRF deaths during 34 980 246 person-years of follow-up. The mortality rate of CRF was 0.64 cases per 100 000 person-years. Adjusted hazard ratios (HRs) were 1.75 (95% CI= 1.30-2.36) for women who gave birth between 26 and 30 years, 2.52 (95% CI=1.57-4.04) for women who gave birth after 30 years, respectively, when compared with women who gave birth younger than 25 years. Adjusted HRs were 0.47 (95% CI= 0.33-0.66) for women who had two children, and 0.40 (95% CI=0.28-0.58) for women with three or more births, respectively, when compared with women who had given birth to only one child. There was a significant decreasing trend in the HRs of CRF death with increasing parity.

CONCLUSIONS

This study provides evidence that reproductive factors (parity and early age at first birth) may confer a protective effect on the risk of CRF death.