Twin chorionicity and the risk of adverse perinatal outcome

Objective: To evaluate the impact of chorionicity on the perinatal outcomes of twin pregnancies complicated by twin-twin transfusion syndrome (TTS) or selective intrauterine growth restriction (sIUGR). Method: Pregnancies with 127 monochorionic (MC) and 109 dichorionic (DC) twins were followed up, and TTS and sIUGR incidence as welt as morbidity and mortality were evaluated. Results: The incidence of intrauterine fetal death was higher in MC than in DC pregnancies (6.5% vs. 1%), and higher in MC pregnancies complicated by TTS (5 deaths in 10 pregnancies [50%]) or sIUGR (2 in 9 [22%]). The incidence of sIUGR was similar in MC and DC pregnancies (7% vs. 5%), and the incidence of TTS was 8% in MC pregnancies (95% confidence inter-vat, 3.2-12.8). Neonatal neurological and respiratory morbidity was higher among MC twins, and the increase in neonatal complications was linked to TTS and sIUGR. Uncomplicated MC and DC pregnancies had similar perinatal, outcomes. Conclusion: The incidence of neonatal complications was higher in MC twins born of pregnancies complicated by TTS or sIUGR. Although the incidence of sIUGR was similar in MC and DC pregnancies, there was a trend towards worse outcomes in MC pregnancies affected by sIUGR. (c) 2006 International Federation of Gynecology and Obstetrics. Published by Elsevier Ireland Ltd. All rights reserved.