Monochorionic diamniotic in vitro fertilization twins have a decreased incidence of twin-to-twin transfusion syndrome

ObjectiveTo compare the incidence of twin-to-twin transfusion syndrome (TTTS) in spontaneous versus IVF-conceived twin pregnancies.DesignRetrospective multicenter study.SettingUniversity-affiliated tertiary medical centers.Patient(s)Women admitted for 11-14 week's scan between January 1997 and July 2013 who were diagnosed with monochorionic (MC) diamniotic twin pregnancies.Intervention(s)None.Main Outcome Measure(s)Mode of conception, TTTS.Result(s)The study cohort included 327 pregnant women with live MC diamniotic twins. Of them, 284 (86.9%) and 43 (13.1%) were spontaneous and IVF conceived, respectively. The mean maternal age was significantly higher in IVF compared with in spontaneously conceived pregnancies (33.8 ± 5.5 vs. 31.6 ± 5.4, respectively). Thirty-seven twins (11.3%) had TTTS, of whom 36/284 (12.7%) versus 1/43 (2.3%) were spontaneously and IVF conceived, respectively. The mean week of delivery was significantly lower in MC twins diagnosed with TTTS compared with those without TTTS (32.7 ± 3.3 vs. 35.5 ± 2.5, respectively). Furthermore, there was a significantly higher birthweight discordancy in twins diagnosed with TTTS compared with those without (20.6% vs. 11%, respectively).Conclusion(s)The significantly lower proportion of TTTS found in IVF-conceived twins may suggest a different embryological process that lies at the core of IVF conception of monozygotic twinning.