Preterm delivery is associated with an increased risk of epithelial ovarian cancer among parous women

• Published in: International journal of cancer 2018-10, Vol.143 (8), p.1858-1867
• Main Authors: Sköld, Camilla, Bjørge, Tone, Ekbom, Anders, Engeland, Anders, Gissler, Mika, Grotmol, Tom, Madanat‐Harjuoja, Laura, Gulbech Ording, Anne, Stephansson, Olof, Trabert, Britton, Tretli, Steinar, Troisi, Rebecca, Toft Sørensen, Henrik, Glimelius, Ingrid
• Format: Article
• Language: English
• Subjects: Adult; Age Factors; Aged; Birth; Births; Cancer; Carcinoma, Ovarian Epithelial - etiology; Case-Control Studies; Denmark; Epithelium; Etiology; Female; Finland; Health risk assessment; Health risks; Humans; Logistic Models; Medical research; Middle Aged; Norway; Odds Ratio; Offspring; Ovarian cancer; Ovarian Neoplasms - etiology; Parity; Parity - physiology; Parturition; Placenta; Placenta - physiopathology; Population studies; Pre-eclampsia; Preeclampsia; Pregnancy; Premature Birth - physiopathology; Risk Factors; Sweden; Tumors; Womens health
• ISSN: 0020-7136; 1097-0215; 1097-0215
• DOI: 10.1002/ijc.31581

Epithelial ovarian cancer is a fatal disease of largely unknown etiology. Higher parity is associated with reduced risk of ovarian cancer. However, among parous women, the impact of pregnancy‐related factors on risk is not well understood. This population‐based case–control study included all parous women with epithelial ovarian cancer in Denmark, Finland, Norway and Sweden during 1967–2013 (n = 10,957) and up to 10 matched controls (n = 107,864). We used conditional logistic regression to estimate odds ratios (ORs) with 95% confidence intervals (CIs) for pregnancy‐related factors and ovarian cancer risk by histological subtype. Preterm delivery was associated with an increased risk [pregnancy length (last pregnancy) ≤30 vs. 39–41 weeks, OR 1.33 (95% CI 1.06–1.67), adjusted for number of births]; the OR increased as pregnancy length decreased (p for trend