HbH hydrops foetalis represents a subtype of HbH disease characterized by severe foetal haemolytic anaemia, which can lead to hydrops foetalis [41–43]. HbH hydrops foetalis typically results from a compound heterozygosity involving α⁰-thalassaemia and a hyper-unstable α-globin variant. Foetuses with HbH hydrops foetalis suffer from severe haemolytic anaemia and may exhibit congenital abnormalities, similar to those observed in Hb Bart’s hydrops foetalis. Their Hb analysis reveals Hb Bart’s levels of 30–60%, alongside the presence of HbF and HbA [41, 43]. Intrauterine transfusion can help improve perinatal outcomes. Patients with HbH hydrops foetalis who survive the perinatal period typically remain transfusion-dependent in the long term.