Does pregnancy induce the shedding of premalignant ovarian cells?

Epidemiology. 2003 Mar;14(2):168-73. doi: 10.1097/01.EDE.0000050701.99792.95.


Background: High parity is associated with reduced risk of ovarian cancer. One hypothesis is that pregnancy is associated with clearance of a fraction of the genetically modified (premalignant) cells from the ovaries.

Methods: We evaluated this hypothesis using a model that estimates the cell clearance fraction at first and second pregnancy according to age at pregnancy. The model was fitted using reproductive history data from a cohort of 1.5 million Danish women born between 1935 and 1978 and followed for 28.7 million person-years. During this follow-up period, 2,035 developed invasive ovarian cancer.

Results: We found the model to have a satisfactory fit despite the very few parameters involved. The model estimated similar cell clearance fractions for the first and second pregnancy and decreasing clearance with later age at pregnancy.

Conclusion: The relation of pregnancy history to risk of ovarian cancer can be well described by a cell clearance model that allows the cell clearance fraction to decrease with age at pregnancy.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Denmark / epidemiology
  • Female
  • Humans
  • Maternal Age
  • Models, Statistical
  • Ovarian Neoplasms / epidemiology
  • Ovarian Neoplasms / pathology*
  • Parity*
  • Pregnancy
  • Registries
  • Risk Factors