Twin births, sex of children and maternal risk of ovarian cancer: a cohort study in Norway.
In a follow-up of 1,208,001 women aged 20-74 years, no significant association was found between twin births (112 cases) and risk, though those with twin girls had a non-significantly higher risk than those with singleton births; among the latter, those with girls only had a higher risk of endometrioid tumours (incidence rate ratio 1.35; 95% confidence interval 1.03-1.76, based on 475 cases) than women with boys only.
Albrektsen
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Department of Mathematics, University of Bergen, Johannes Brunsgate 12, 5008 Bergen, Norway. msega@uib.no
Heuch
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Thoresen
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Kvåle
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D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009035:Mothers; D009664:Norway / Q000453:epidemiology; D010051:Ovarian Neoplasms / Q000453:epidemiology*; D010298:Parity; D011247:Pregnancy; D012042:Registries; D012307:Risk Factors; D012727:Sex Characteristics; D014427:Twins