It is most probable that she staid with her until she was brought to bed, not leaving her just at the time of her travail, but she staid not long after, but went home: by this time she must herself know that she was with child; and here in the true order of the history cometh in what we had Matthew 1:18-25: See Poole on "Matthew 1:18" and following verses to Matthew 1:25.
Related Commentaries of Luke 1:56
Luke 1:56
56 And Mary abode with her about three months, and returned to her own house.