expression, godan verb (-ru)
give birth; have a baby
Idiomatic expression literally meaning 'to become two bodies', used for a pregnant woman giving birth. Slightly old-fashioned or literary.
彼女は無事に身二つになって、元気な男の子を産んだ。
She safely gave birth and delivered a healthy baby boy.
Standard kanji spelling for this idiomatic expression.
Mixed kanji-kana spelling; less common but still used.
From 身 (body) + 二つ (two) + になる (to become), literally 'to become two bodies'. The exact origin is uncertain, but it is a traditional Japanese expression for childbirth.