I found this in the NAB-RE:
- [1:5–2:52] Like the Gospel according to Matthew, this gospel opens with an infancy narrative, a collection of stories about the birth and childhood of Jesus. The narrative uses early Christian traditions about the birth of Jesus, traditions about the birth and circumcision of John the Baptist, and canticles such as the Magnificat (Lk 1:46–55) and Benedictus (Lk 1:67–79), composed of phrases drawn from the Greek Old Testament. It is largely, however, the composition of Luke who writes in imitation of Old Testament birth stories, combining historical and legendary details, literary ornamentation and interpretation of scripture, to answer in advance the question, “Who is Jesus Christ?” The focus of the narrative, therefore, is primarily christological. In this section Luke announces many of the themes that will become prominent in the rest of the gospel: the centrality of Jerusalem and the temple, the journey motif, the universality of salvation, joy and peace, concern for the lowly, the importance of women, the presentation of Jesus as savior, Spirit-guided revelation and prophecy, and the fulfillment of Old Testament promises. The account presents parallel scenes (diptychs) of angelic announcements of the birth of John the Baptist and of Jesus, and of the birth, circumcision, and presentation of John and Jesus. In this parallelism, the ascendency of Jesus over John is stressed: John is prophet of the Most High (Lk 1:76); Jesus is Son of the Most High (Lk 1:32). John is great in the sight of the Lord (Lk 1:15); Jesus will be Great (a LXX attribute, used absolutely, of God) (Lk 1:32). John will go before the Lord (Lk 1:16–17); Jesus will be Lord (Lk 1:43; 2:11).
Personally, although Luke does not indicate it, I feel certain that Mary would have been accompanied on the trip just because of the danger and social mores for women. I don’t believe that the lack of mention means that she was aline. It just wasn’t necessary to the points Luke wanted to make.
The Gospel does not indicate that Mary went to Elizabeth out of Elizabeth’s need. The pregnancy of Elizabeth was a sign in confirmation of what the Angel had told her. She may have wished to see for herself. I assume she was also excited to find that Elizabeth was finally pregnant. That must have been amazing to those who knew of her barrenness.
Elizabeth had others nearby to attend to her at the time of John’s birth:
Luke 1: 57-58
When the time arrived for Elizabeth to have her child she gave birth to a son. Her neighbors and relatives heard that the Lord had shown his great mercy toward her, and they rejoiced with her.
I am not nearly as disturbed by the question of historicity as I am by the suggestion that Mary was not a complete model of charity. The idea that she would leave Elizabeth without help during the birth seems opposed to our belief in her sinkessness.
CCC 493 “By the grace of God Mary remained free of every personal sin her whole life long.”