生後(せいご)

せいご
noun
after birth; (age) since birth
time-periodhealth
1. after birth; since birth (giving a baby's or animal's age)
The time since a baby or young animal was born; used with a number to give its age in days, weeks or months.
生後(せいご)三(さん)か月(げつ)の赤(あか)ちゃん。
A three-month-old baby.
子犬(こいぬ)は生後(せいご)二(に)か月(げつ)で家(いえ)に来(き)た。
The puppy came to our house when it was two months old.
この病気(びょうき)は、生後(せいご)まもなく見(み)つかることが多(おお)い。
This illness is often discovered shortly after birth.

生(せい) (birth) + 後(ご) (after).

Common patterns

  • 生後(せいご) + number + か月(げつ) / 日(にち): ~ months / days old
  • 生後(せいご)まもなく: shortly after birth
  • 生後(せいご)一年未満(いちねんみまん): under one year old

Watch out

生前(せいぜん) does not mean "before birth": it means "while (someone now dead) was alive". The opposite of 生後(せいご) is 出生前(しゅっしょうまえ) or 生(う)まれる前(まえ).

general
Added 2026.10.10 5:09 · Revised 2026.10.10 5:11
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