Zechariah and Elisabeth had one child, John, who was (as with Sarai) born in advanced age. For nothing is impossible to God. Part of the gospel story is that Mary gained courage to accept the word of God and the Holy Spirit because before that Elizabeth had conceived.
Elizabeth gave birth to the last prophet of Israel: and Mary to the beginning of the new covenant..
67 And his father Zacharias was filled with the Holy Spirit, and prophesied, saying:
68 “Blessed be the Lord God of Israel, For He has visited us and accomplished redemption for His people,
69 And has raised up a horn of salvation for us In the house of David His servant—
70 As He spoke by the mouth of His holy prophets from of old—
71 Salvation from our enemies, And from the hand of all who hate us;
72 To show mercy toward our fathers, And to remember His holy covenant,
73 The oath which He swore to Abraham our father,
74 To grant us that we, being rescued from the hand of our enemies, Might serve Him without fear,
75 In holiness and righteousness before Him all our days.
76 “And you, child, will be called the prophet of the Most High; For you will go on before the Lord to prepare His ways;
77 To give to His people the knowledge of salvation By the forgiveness of their sins,
78 Because of the tender mercy of our God, With which the Sunrise from on high will visit us,
79 To shine upon those who sit in darkness and the shadow of death, To guide our feet into the way of peace.”
80 And the child continued to grow and to become strong in spirit, and he lived in the deserts until the day of his public appearance to Israel.