All three babies share the same placenta and chorion. In separate amniotic sacs, or two or more babies can share an amniotic sac.

Can you have a natural birth with quadruplets?

The couple conceived quadruplets naturally, an extremely rare occurrence that happens in just 1 in 700,000 pregnancies. Approximately 90 percent of quadruplets are conceived with the assistance of medical technology.

What happens to the placenta in multiple births?

Blood vessels connect within the placenta and divert blood from one fetus to the other. It occurs in about 15 percent of twins with a shared placenta. In TTTS, blood is shunted from one fetus to the other through blood vessel connections in a shared placenta.