title: Monozygotic twins in infertile patients with advanced maternal age: case reports and review of the literature.
abstract: OBJECTIVE
  To report two cases of successful monozygotic twin pregnancies in women undergoing infertility treatment and to review possible etiologic factors.
  
  
  METHODS
  Case report and review of the literature.
  
  
  METHODS
  University of Toronto-affiliated infertility clinic.
  
  
  METHODS
  A 43-year-old woman and a 44-year-old woman with history of secondary infertility.
  
  
  METHODS
  In vitro fertilization and ET.
  
  
  METHODS
  Monozygotic twin pregnancy.
  
  
  RESULTS
  Delivery of two sets of monozygotic twins.
  
  
  CONCLUSIONS
  The only identified potential risk factors for monozygotic twins are maternal age and assisted reproductive technologies. Both patients reported here were aged >40 years and underwent assisted reproduction procedures, including high-dose gonadotropin stimulation, embryo culture, and, in case 2, intracytoplasmic sperm injection plus assisted hatching.
authors.affiliation: Toronto Centre for Advanced Reproductive Technology, University of Toronto, Toronto, Ontario, Canada; Division of Reproductive Sciences, Department of Obstetrics and Gynecology, University of Toronto, Toronto, Ontario, Canada. Electronic address: navid.esfandiari@utoronto.ca.
authors.forename: Navid
authors.initials: N
authors.lastname: Esfandiari
authors.affiliation: Toronto Centre for Advanced Reproductive Technology, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Monica
authors.initials: M
authors.lastname: Kapoor
authors.affiliation: Toronto Centre for Advanced Reproductive Technology, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Hasan
authors.initials: H
authors.lastname: Burjaq
authors.affiliation: Toronto Centre for Advanced Reproductive Technology, University of Toronto, Toronto, Ontario, Canada; Division of Reproductive Sciences, Department of Obstetrics and Gynecology, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Paul
authors.initials: P
authors.lastname: Chang
authors.affiliation: Toronto Centre for Advanced Reproductive Technology, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Lynda
authors.initials: L
authors.lastname: Gotlieb
authors.affiliation: Toronto Centre for Advanced Reproductive Technology, University of Toronto, Toronto, Ontario, Canada; Division of Reproductive Sciences, Department of Obstetrics and Gynecology, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Robert F
authors.initials: RF
authors.lastname: Casper
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D007247:Infertility, Female / Q000628:therapy*; D008423:Maternal Age; D011247:Pregnancy; D011256:Pregnancy Outcome; D027724:Reproductive Techniques, Assisted; D012307:Risk Factors; D014430:Twins, Monozygotic