It appears to be uncertain whether the journey of Mary with her husband was obligatory or voluntary. . . . Women were liable to a capitation tax, if this enrolment also involved taxation. But, apart from any legal necessity, it may easily be imagined that at such a moment Mary would desire not to be left alone. The cruel suspicion of which she had been the subject, and which had almost led to the breaking off of her betrothal (Matt. 1: 19) would make her cling all the more to the protection of her husband.
Source: Farrar in The Life of Christ, footnote p 24
Contributed by: Zaady