Population
The study group consisted of 11 patients with monochorionic-diamniotic twins that were diagnosed with severe TTTS at stages II or III according to the Quintero classification 24 between 2004 and 2015. We collected the following maternal and perinatal data: maternal age, parity, stage of TTTS at diagnosis, gestational age at the first controlled AR procedure, number of controlled AR procedures, volume removed per one AR session, gestational age at delivery and birth weight for each twin (see Table 1). All the surviving twins were recruited for a long-term neurodevelopmental follow up. The study was approved by the ethics committee of the Tel Aviv Sourasky Medical Center (No. 04-220) and informed consents were signed by the participants.