Why it matters in the Letby case
Several Letby cases involve twins. Post-conviction expert review argues some of those cases are consistent with TTTS and surviving-twin instability after sibling death.
Medical explainer
Twin-to-twin transfusion syndrome (TTTS)
Twin-to-twin transfusion syndrome (TTTS) is a complication of monochorionic twin pregnancies in which blood is shunted unequally between twins, producing instability that can persist post-delivery.
Scientific literature2Expert/professional
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Prosecution position
Several indicted cases involve twins, and the Crown attributed their deteriorations to deliberate harm rather than to shared placental pathology.
Expert challenge / post-conviction reading
Post-conviction review argues some of those cases are consistent with twin-to-twin transfusion syndrome and with the instability a surviving twin experiences after a sibling's death — both recognised complications of monochorionic twin pregnancy.
What remains uncertain
TTTS is diagnosed antenatally and by placental examination. Where that evidence was not gathered at the time, the argument rests on the clinical picture being consistent with it rather than on a confirmed diagnosis.
Common questions
What is twin-to-twin transfusion syndrome?
A complication of monochorionic (shared-placenta) twin pregnancy in which blood is unequally shared between the twins through connecting placental vessels, leaving one over- and one under-perfused.
Why would one twin destabilise after the other dies?
Because the shared circulation means the death of one twin can cause an acute haemodynamic change in the survivor. This is a recognised phenomenon, not a rare curiosity.
Was TTTS diagnosed in the indicted cases?
The post-conviction argument is that the clinical picture in some cases is consistent with it, and that the obstetric evidence needed to test that was largely absent from the trial.
Does this apply to all the twin cases?
No. It is offered as a differential for some, not as a general explanation.
Related reading
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