Parity, age at first birth, and risk of death from liver cancer: Evidence from a cohort in Taiwan.
OBJECTIVE
The present study was undertaken to examine whether there is an association between parity and age at first birth and risk of liver cancer.


METHODS
The study cohort consisted of 1,292,462 women who had a first and singleton childbirth between 1 January 1978 and 31 December 1987. We tracked each woman from the time of their first childbirth to 31 December 2007, and their vital status was ascertained by linking records with the computerized mortality database. Cox proportional hazard regression models were used to estimate the relative risks (RR) of death from liver cancer associated with parity and age at first birth.


RESULTS
There were 826 liver cancer deaths during 32,464,186.58 person-years of follow-up. The mortality rate of liver cancer was 2.54 cases per 100,000 person-years. The adjusted RR was 1.59 (95% confidence interval [CI] = 1.36-1.86) for women who gave birth between 26 and 30, 2.41 (95% CI = 1.81-3.20) for women who gave birth between 31 and 35, and 6.26 (95% CI = 4.27-9.19) for women who gave birth after 35 years of age, respectively, when compared with women who gave birth at less than 25 years of age. The adjusted RR was 0.72 (95% CI = 0.59-0.87) for women who had two to three children, and 0.63 (95% CI = 0.47-0.84) for women with four or more births, respectively, when compared with women who had given birth to only one child.


CONCLUSIONS
The present study suggests that reproductive factors (parity and early age at first birth) may confer a protective effect on the risk of liver cancer.
Department of Obstetrics and Gynecology, Chang Gung Memorial Hospital- Kaohsiung Medical Center, College of Medicine, Chang Gung University, Kaohsiung, Taiwan.
Chen-Hsuan
CH
Wu
Te-Fu
TF
Chan
Chan-Chao
CC
Changchien
Chun-Yuh
CY
Yang
D000328:Adult; D000367:Age Factors; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008113:Liver Neoplasms / Q000401:mortality*; D010298:Parity; D011247:Pregnancy; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012042:Registries; D018570:Risk Assessment; D012307:Risk Factors; D013624:Taiwan / Q000453:epidemiology; D013997:Time Factors; D055815:Young Adult