Sometimes it seems like twins share everything, but usually not amniotic sacs!
Kate and Annie Carlson are monoamniotic twins, meaning they suffered from a rare disorder in which they didn't get their own individual amniotic sacs and were forced to share one!
Delivery team leader Dr. Susan Crowe says:
"Having a set of monoamniotic twins can be dangerous and unpredictable. With no membrane dividing them, the obstetrician has to balance the risk of prematurity with the risk of a cord event."
Unfortunately, that's exactly what happened.