noun, adverb
subsequently; additionally; after that
Used to indicate that something happens or is done after a previous event or action, often in a sequential or additive sense. Can function as a noun or adverb.
事前後に詳細をお知らせします。
We will inform you of the details subsequently.
事前後の対応について話し合った。
We discussed the subsequent response.
後日 means 'at a later date' and is often used for future follow-ups, whereas 事前後 can refer to any subsequent event regardless of timing.
Compound of 事前 (jizen, 'prior') and 後 (go, 'after'), literally meaning 'after the prior matter'. The exact historical derivation is uncertain, but the word is used in formal contexts to denote subsequence.