Combined oral contraceptive use before the first birth and epithelial ovarian cancer risk

Br J Cancer. 2017 Jan 17;116(2):265-269. doi: 10.1038/bjc.2016.400. Epub 2016 Dec 13.


Background: Combined oral contraceptive (COC) use reduces epithelial ovarian cancer (EOC) risk. However, little is known about risk with COC use before the first full-term pregnancy (FFTP).

Methods: This Canadian population-based case-control study (2001-2012) included 854 invasive cases/2139 controls aged ⩾40 years who were parous and had information on COC use. We estimated odds ratios (aORs) and 95% confidence intervals (CI) adjusted for study site, age, parity, breastfeeding, age at FFTP, familial breast/ovarian cancer, tubal ligation, and body mass.

Results: Among parous women, per year of COC use exclusively before the FFTP was associated with a 9% risk reduction (95% CI=0.86-0.96). Results were similar for high-grade serous and endometrioid/clear cell EOC. In contrast, per year of use exclusively after the FFTP was not associated with risk (aOR=0.98, 95% CI=0.95-1.02).

Conclusions: Combined oral contraceptive use before the FFTP may provide a risk reduction that remains for many years, informing possible prevention strategies.

MeSH terms

  • Adult
  • Aged
  • Birth Order*
  • Breast Neoplasms / epidemiology
  • Canada / epidemiology
  • Carcinoma, Ovarian Epithelial
  • Case-Control Studies
  • Contraceptives, Oral, Combined / therapeutic use*
  • Female
  • Humans
  • Middle Aged
  • Neoplasms, Glandular and Epithelial / epidemiology*
  • Ovarian Neoplasms / epidemiology*
  • Parity
  • Pregnancy
  • Risk Factors
  • Sterilization, Tubal / statistics & numerical data
  • Young Adult


  • Contraceptives, Oral, Combined

Supplementary concepts

  • Breast Cancer, Familial