NPPB and twin to twin transfusion syndrome: Previous studies have reported a good correlation between amniotic fluid NT-proBNP levels and the severity of twin-twin transfusion syndrome in monochorionic diamniotic twin pregnancies (Bajoria et al., 2002; Delabaere et al., 2010; Habli et al., 2010; Van Mieghem et al., 2010).