title: High incidence of monozygotic twinning after assisted reproduction is related to genetic information, but not to assisted reproduction technology itself.
abstract: OBJECTIVE
  To study the incidence of monozygotic twinning (MZT) in patients using in vitro fertilization, relative to their age, genetic background, ovarian function, and assisted reproductive techniques used.
  
  
  METHODS
  Analysis of a collected database.
  
  
  METHODS
  Infertility treatment center.
  
  
  METHODS
  A total of 1,876 patients receiving infertility treatment between 2000 and 2012. Pregnancies with monozygotic twins (A: 23) were compared with deliveries of dizygotic twins (B: 423), singleton pregnancies (C: 880), and aborted pregnancies (D: 389).
  
  
  METHODS
  None.
  
  
  METHODS
  A genetic survey on multiple pregnancies in the extended family. Measures were micromanipulation technique, the length of embryo cultivation, type of cultivation media, basal follicle-stimulating hormone level, estradiol level on the day of human chorionic gonadotropin administration, number of oocytes, total consumption of gonadotropins, and consumption of gonadotropins needed for recovery of 1 oocyte.
  
  
  RESULTS
  No differences were found between the incidence of MZT in cycles that did vs. did not use micromanipulation techniques. In addition, the length of embryo cultivation or type of cultivation media used did not affect the results. Estradiol levels and implantation rates were significantly higher in group A. The incidence of MZT in families in group A was significantly higher than that in groups B and C.
  
  
  CONCLUSIONS
  We propose that the high incidence of MZT in infertility-clinic patients is conditioned by hereditary factors, and good ovarian function only facilitates the expression. The resulting recommendation is that young women with a positive family history and good ovarian function undergo elective single-embryo transfer, and proper counseling is advisable.
authors.affiliation: Fertimed Center for Reproductive Medicine and Infertility, Olomouc, Czech Republic; Department of Obstetrics and Gynaecology, Prostějov, Czech Republic. Electronic address: ales.sobek@seznam.cz.
authors.forename: Aleš
authors.initials: A
authors.lastname: Sobek
authors.affiliation: Fertimed Center for Reproductive Medicine and Infertility, Olomouc, Czech Republic.
authors.forename: Blažena
authors.initials: B
authors.lastname: Zbořilová
authors.affiliation: Department of Midwifery, Faculty of Health Sciences, Palacky University Olomouc, Olomouc, Czech Republic.
authors.forename: Martin
authors.initials: M
authors.lastname: Procházka
authors.affiliation: Fertimed Center for Reproductive Medicine and Infertility, Olomouc, Czech Republic.
authors.forename: Eva
authors.initials: E
authors.lastname: Šilhánová
authors.affiliation: Fertimed Center for Reproductive Medicine and Infertility, Olomouc, Czech Republic.
authors.forename: Olga
authors.initials: O
authors.lastname: Koutná
authors.affiliation: Department of Paediatrics, University Hospital Olomouc, and Faculty of Medicine and Dentistry, Palacky University Olomouc, Olomouc, Czech Republic.
authors.forename: Eva
authors.initials: E
authors.lastname: Klásková
authors.affiliation: Department of Ecology and Environmental Sciences, Palacky University Olomouc, Olomouc, Czech Republic; Institute of Vertebrate Biology, Academy of Sciences of the Czech Republic, Studenec, Czech Republic.
authors.forename: Emil
authors.initials: E
authors.lastname: Tkadlec
authors.affiliation: Fertimed Center for Reproductive Medicine and Infertility, Olomouc, Czech Republic.
authors.forename: Aleš
authors.initials: A
authors.lastname: Sobek
mesh_terms: D000328:Adult; D004624:Embryo Transfer / Q000379:methods / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D015994:Incidence; D007231:Infant, Newborn; D008297:Male; D011247:Pregnancy; D018873:Pregnancy Rate; D059285:Pregnancy, Twin / Q000235:genetics* / Q000706:statistics & numerical data*; D027724:Reproductive Techniques, Assisted / Q000706:statistics & numerical data*; D038522:Twinning, Monozygotic / Q000235:genetics; D014430:Twins, Monozygotic / Q000235:genetics / Q000706:statistics & numerical data
keywords: Monozygotic twins; assisted reproduction techniques; genetics; incidence; infertility