Just some further reading on Vanishing Twin Syndrome (VTS).
It is estimated that 1 in 8 twins end up with VTS, where one twin absorbs the other. But the data is based on evidence where a second heartbeat disappeared or a semi-absorbed fetus is found in the womb.
But some people theorize that this is more common and the twin is absorbed completely, sometimes even before the ultrasound detects a heartbeat. Any of us could have absorbed a twin in the womb.
VTS has been a common horror trope in films like The Unborn, Malignant, and Let Her Out.
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