
The Small Anastomosis Hypothesis: How Four 2025–2026 Studies Reframed Prognosis in Twin Anemia–Polycythemia Sequence
Identical twins who share one placenta sometimes also share blood vessels inside it, and in a rare condition called twin anemia–polycythemia sequence a few of those vessels let red blood cells drift slowly from one twin to the other over many weeks. One baby ends up short of red cells and the other…