For my child (περ του εμου τεκνου). Tender and affectionate reference to Onesimus as his spiritual child.

Whom I have begotten in my bonds (ον εγεννησα εν τοις δεσμοις). First aorist active indicative of γενναω, to beget. See 1. Corinthians 4:15 for this figurative sense. Paul is evidently proud of winning Onesimus to Christ though a prisoner himself.