Outcome of monochorionic-biamniotic twins conceived by assisted reproduction: a population-based study

Objecive: To evaluate the perinatal outcome of monochorionic- diamniotic twins conceived by assisted reproduction technology (ART). Methods: We compared data from a national population- based perinatal registry on perinatal outcomes of monochorionic-diamniotic twins conceived by ART with their dichorionic counterparts and with spontaneous monochorionic-diamniotic twins. We compared maternal characteristics, pregnancy complications and perinatal outcomes. Results: Monochorionic-diamniotic twin pregnancies (n = 45) comprised 5.5% of all ART twins, and 9.3% of all monochorionic twins in this dataset. ART does not appear to increase the already high risk of monochorionicity compared to spontaneous conception, with the latter having an increased incidence for birth weight <1500 g [odds ratio (OD) 2.6, 95% confidence interval (CI) 1.2-5.4]. Conclusion: Our results disagree with hospital-based data and suggest that monochorionic-diamniotic twins following ART are not at increased risk of adverse perinatal outcomes compared to spontaneous monochorionic-diamniotic twins as well as to dichorionc twins conceived by ART.