The relationship between twin births and maternal risk of breast cancer: A meta-analysis

Research output: Contribution to journalArticle

6 Citations (Scopus)


Women who undergo a greater number of menstrual cycles may be at increased risk of breast cancer, possibly due to cumulative exposure to ovarian hormones. Pregnancy reduces the lifetime number of menstrual cycles and also influences the levels of ovarian hormones. Twin pregnancies differ from singleton pregnancies in both hormone levels and perinatal changes. To date, a meta-analysis on the effects of twin birth on the risk of maternal breast cancer has not been conducted. Among 17 relevant publications identified in a systematic search, some suggest that twin births may be associated with lower breast cancer risk but others do not; therefore, the results are inconclusive. Although our pooled results of all 17 published studies did not show a reduced maternal risk of breast cancer for twin births (HR 0.94; 95% CI = 0.87-1.02; P = 0.127), a trend toward reduced maternal risk of breast cancer was identified in a subgroup analysis of cohort studies (HR 0.91; 95% CI = 0.83-1.01; P = 0.068). The results of this meta-analysis suggest that twin pregnancy does not significantly decrease the maternal risk of breast cancer.

Original languageEnglish
Pages (from-to)671-677
Number of pages7
JournalBreast Cancer Research and Treatment
Issue number2
Publication statusPublished - 2012 Jan


  • Breast cancer
  • Meta-analysis
  • Twin births

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

Fingerprint Dive into the research topics of 'The relationship between twin births and maternal risk of breast cancer: A meta-analysis'. Together they form a unique fingerprint.

  • Cite this