noun
umbilical cord
Refers to the physical cord connecting a fetus to the placenta. Also used in the idiom へその緒を切る (to cut the umbilical cord, i.e., to become independent).
赤ちゃんが生まれた後、へその緒を切ります。
After the baby is born, the umbilical cord is cut.
彼はまだ親のへその緒から離れられない。
He still can't cut the umbilical cord from his parents.