Outcome of monochorionic twins conceived by assisted reproduction

Objective: To evaluate monochorionic twins conceived by assisted reproductive technology (ART). Design: We compared perinatal outcomes of monochorionic twins conceived by ART with their dichorionic counterparts and with spontaneous monochorionic twins. Setting: Referral center. Patient(s): Mothers to monochorionic and dichorionic twins conceived by ART and spontaneous monochorionic twins. Intervention(s): None. Main Outcome Measure(s): Maternal characteristics, pregnancy complications, and perinatal outcomes. Result(s): Monochorionic twin pregnancies (n = 25) comprise 7.2% of all ART twins and 4.9% of all monochorionic twins in this data set. Monochorionic pairs have a significantly worse outcome compared with dichorionic sets in terms of lower gestational age and birth weight. ART appears to increase the already high risk of monochorionicity compared with spontaneous conception: odds ratio (OR), 2.9 (1.1-7.3) for preterm birth at <32 weeks and OR, 5.9 (2.5-1.49) for birth weight <1,500 g. Conclusion(s): Monochorionic twins after ART are at increased risk of adverse perinatal outcomes compared with spontaneous monochorionic twins and with dichorionic twins conceived by ART. (C) 2015 by American Society for Reproductive Medicine.