Zechariah was a priest (Levite), Elizabeth, his wife a descendant of Aaron, also a Levite
The Bible says that both were righteous, living blamelessly but they had no children, which at that time was said to be a curse or condemnation from God.
“…once when he (Zechariah) was serving as priest (in the Temple), he was chosen by lot to offer incense in the sanctuary…the whole assembly of the people were praying outside…”Do not be afraid, Zechariah, for your prayer has been heard.” (the angel Gabriel spoke to Zechariah)…” After serving his time in the Temple, Elizabeth conceived a child, even though both she and Zechariah were old. “for five months Elizabeth remained in seclusion.”
Two elderly people doing their best to serve their Lord, yet for all the joy and goodness of their lives together, they had no children. They persisted in honoring God. When Elizabeth conceives, did she wonder how and why? Did Zechariah tell Elizabeth about the angel’s message? Did Elizabeth believe that her days were now filled with wonder?
So many questions which the Bible does not answer.