Ultrasound examination had demonstrated that all three fetuses in each pregnancy were alive. There were no obvious defects in any of the separate fetuses. In the monochorionic twins, one fetus had diaphragmatic hernia, one had generalized oedema with nuchal translucency thickness of 12 mm and in 8 cases there were early signs of twin-to-twin transfusion syndrome or selective fetal
growth restriction with large discordance in crown-rump length (>10%) and subjectively assessed discordance inamniotic fluid volume and/or reversed a-wave in the ductus venosus in one of the fetuses.