生後 せいご Meanings Noun, Adverb post-natal; since birth Kanji 生 life. Read as セイ. 後 after. Read as ゴ. Example sentences この赤ちゃんは生後3週間です。This baby is 3 weeks old. 新しく小犬を飼いました。生後3ヶ月です。We have a new puppy. He is about 12 weeks old. 生後6か月の息子に歯が生えかかっています。My six-month old son is teething. 祖父は私の生後間もない頃に亡くなった。My grandfather died shortly after my birth. Jinuma: Japanese Dictionary · Word lists