What does Luke 1:42 mean?

The aging wife of a priest, Elizabeth, is six months pregnant (Luke 1:36). This was a miraculous event, as she had been unable to have children prior to this (Luke 1:5–7). An angel announced that she and her husband would conceive a son who would fulfill important roles in biblical prophecy (Luke 1:13–17). Elizabeth has just been visited by her relative Mary, an unmarried virgin (Luke 1:26–27). Mary has also been given news by an angel: she will bear the Son of God, the Messiah (Luke 1:30–33). When Mary announced herself, both Elizabeth and her unborn child reacted immediately (Luke 1:40–41). Both Jesus Christ and John the Baptist, though yet unborn, are living people with their own identities.

Elizabeth's response is motivated by the Holy Spirit. At the moment, Mary has just entered the home and spoken a greeting. She has not, it seems, made any mention of her own pregnancy. And yet, Elizabeth responds by celebrating the fact that Mary is pregnant. She does this with a shout: the Greek text makes a point of saying she is speaking in a loud voice.

Twice in this verse, Elizabeth uses the Greek root word eulogeo, which refers to praise and approval. This is the same word from which we derive the English term eulogy, where someone speaks approvingly of the deceased at a funeral. Her reaction also implies a compliment for Mary's faithful reaction. Her own husband, Zechariah, initially reacted with doubt (Luke 1:18) and was temporarily rendered mute (Luke 1:19–20). Mary reacted to the angel's message with a more trusting question (Luke 1:35), and faithful submission (Luke 1:38).

In the following verse, Elizabeth will further note that the Child whom Mary carries is the Lord (Luke 2:11).