The epidemiology of multiple births

Renata Bortolus, Fabio Parazzini, Liliane Chatenoud, Guido Benzi, Massimiliano Maria Bianchi, Alberto Marini

Research output: Contribution to journalArticlepeer-review


On the basis of MEDLINE and manual searches, we examined the main papers in the English literature regarding risk factors for spontaneous (i.e. not related to fertility drug use) multiple births. The constant frequency of monozygotic (MZ) pregnancies over time and in different geographical areas suggests that the determination of MZ twins is largely unchanged over time, and that a genetic mechanism may have a role. In contrast, temporal and geographical trends observed in dizygotic (DZ) pregnancies suggest that environmental factors play a role in determining this condition. At present, maternal age and hereditary components are the best-defined determinants for spontaneous multiple births.

Original languageEnglish
Pages (from-to)179-187
Number of pages9
JournalHuman Reproduction Update
Issue number2
Publication statusPublished - Mar 1999


  • Epidemiology
  • Multiple births
  • Risk factors

ASJC Scopus subject areas

  • Obstetrics and Gynaecology
  • Reproductive Medicine

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