“…1 in 150 births is complicated by mild ABO HDN, characterized by jaundice without anaemia, whereas severe haemolysis will be seen in only 1 in 3000 neonates. It is rarer still for feto‐maternal ABO incompatibility to impact on fetal life with only six case reports to date of hydrops fetalis secondary to ABO incompatibility (Miller & Petrie, 1963; Gilja & Shah, 1988; Sherer et al ., 1991; Stiller et al ., 1996; McDonnell et al ., 1998). None of these case reports involved the use of intra uterine transfusions, and we could find no previous reports of both fetuses in a twin pregnancy being affected.…”