en_tn/mat/01/25.md

he did not know her

This is a euphemism. Alternate translation: "he did not have sexual relations with her" (See: rc://en/ta/man/translate/figs-euphemism)

to a son

"to a male baby" or "to her son." Make sure it is clear that Joseph is not portrayed as the actual father.

Then he called his name Jesus

"Joseph named the child Jesus"