BACKGROUND: Monozygotic twinning is associated with increased perinatal morbidity and mortality. There is evidence that the number of monozygotic twins increases after assisted reproductive techniques. METHODS: We searched PUBMED, MEDLINE, and Scopus from 1987 to 2015 for studies analyzing the incidence and possible etiology of monozygotic twinning in infertility patients and critically reviewed the current state of knowledge. RESULTS AND CONCLUSIONS: Monozygotic twinning is a rare in natural conception but occurs around twice the normal rate after assisted reproduction. Factors associated with this phenomenon remain speculative, though there is some evidence that micromanipulation techniques, prolonged culture, and genetics are involved. In view of the possible complications, adequate pre-conception counselling is advocated.

• Klíčová slova
• incidence, infertility, monozygotic twins, risk factors,
• MeSH
• asistovaná reprodukce škodlivé účinky   MeSH
• dvojčata monozygotní MeSH
• infertilita terapie   MeSH
• lidé MeSH
• rozdělení zygoty genetika   fyziologie   MeSH
• těhotenství s dvojčaty fyziologie   MeSH
• těhotenství MeSH
• věkové faktory MeSH
• Check Tag
• lidé MeSH
• těhotenství MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

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. DESIGN: Analysis of a collected database. SETTING: Infertility treatment center. PATIENT(S): 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). INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): 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. RESULT(S): 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. CONCLUSION(S): 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.

• Klíčová slova
• Monozygotic twins, assisted reproduction techniques, genetics, incidence, infertility,
• MeSH
• asistovaná reprodukce statistika a číselné údaje   MeSH
• dospělí MeSH
• dvojčata monozygotní * genetika   statistika a číselné údaje   MeSH
• incidence MeSH
• lidé MeSH
• novorozenec MeSH
• přenos embrya metody   statistika a číselné údaje   MeSH
• rozdělení zygoty * genetika   MeSH
• těhotenství s dvojčaty genetika   statistika a číselné údaje   MeSH
• těhotenství MeSH
• úhrn těhotenství na počet žen v reprodukčním věku MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mužské pohlaví MeSH
• novorozenec MeSH
• těhotenství MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH