N (%) are reported unless otherwise stated. Excluding: the 3 pregnancies which underwent feticide of the surviving co-twin, 3 that were miscarried, 2 that were a co-twin stillbirth, and the 11 cases for which the outcome data were missing were not included. 1 pregnancy with ‘unclear’ aetiology was included in the ‘All’ column only. Data were missing for one TTTS pregnancy which delivered at 36 weeks and it was not known if delivery was spontaneous or iatrogenic. *28/48 were <34 weeks. †5/19 were <28 weeks. ‘-‘ data not provided to reduce patient identifiability. ‘Complicated’ included pregnancies with TTTS, sIUGR and/or congenital/structural anomalies