noun
quintuplets
Refers to five children born from the same pregnancy. The term is neutral and factual.
彼女は五つ子を出産した。
She gave birth to quintuplets.
五つ子の育児は大変だ。
Raising quintuplets is tough.
Compound of 五つ (itsutsu, 'five') + 子 (ko, 'child'), with rendaku voicing of 子 to ご.