Does the time interval between first and last birth influence the risk of endometrial and ovarian cancer?
BACKGROUND
Age at first and last birth and the number of children are known to influence the risk of endometrial and ovarian cancers. However, it remains unknown whether the difference in years between first and last childbirth plays a role. The Swedish Family-Cancer Database allowed us to carry out the largest study ever on reproductive factors in these cancers.


METHODS
We selected over 5.7 million women from the database. We estimated the effect of number of children, age at birth and difference between age at first and last birth by Poisson regression adjusted for age, period, region and socioeconomic status.


RESULTS
The risk for endometrial cancer is negatively associated with increasing number of children and increasing age at first as well as age at last birth. Weaker associations are found for ovarian cancer. Age at last birth is the factor that shows highest influence. A large difference in first and last childbirth shows a protective effect on the risk of endometrial cancer.


CONCLUSIONS
Our findings suggest that the risk of endometrial cancer is significantly decreased for women having at least a difference of 10 years between their first and last birth. Ovarian cancer does not seem to be influenced by the time interval between first and last birth.
Division of Molecular Genetic Epidemiology, German Cancer Research Center, Im Neuenheimer Feld 580, Heidelberg, Germany. m.bevier@dkfz-heidelberg.de
Melanie
M
Bevier
Jan
J
Sundquist
Kari
K
Hemminki
D000328:Adult; D017677:Age Distribution; D000368:Aged; D001721:Birth Intervals / Q000706:statistics & numerical data*; D016889:Endometrial Neoplasms / Q000453:epidemiology*; D005260:Female; D006801:Humans; D008423:Maternal Age; D008875:Middle Aged; D010051:Ovarian Neoplasms / Q000453:epidemiology*; D010298:Parity; D011247:Pregnancy; D012307:Risk Factors; D012959:Socioeconomic Factors; D013548:Sweden / Q000453:epidemiology; D055815:Young Adult