16 The words “He went” are not in the Greek text, but have been supplied to begin a new sentence in the translation. The Greek sentence is longer and more complex than normal contemporary English usage.
17 Traditionally, “Mary, his betrothed.” Although often rendered in contemporary English as “Mary, who was engaged to him,” this may give the modern reader a wrong impression, since Jewish marriages in this period were typically arranged marriages. The term ἐμνηστευμένῃ (emnēsteumenē) may suggest that the marriage is not yet consummated, not necessarily that they are not currently married. Some read “the betrothed to him wife”; others, simply “his wife.” These readings, though probably not original, may give the right sense.

In other versions

to be registered with Mary, his betrothed, who was with child.

He went there to register with Mary, who was pledged to be married to him and was expecting a child.

to be registered along with Mary, who was engaged to him and was pregnant.

He took with him Mary, to whom he was engaged, who was now expecting a child.

to be registered together with Mary, who was legally promised in marriage to him and was pregnant.

To be taxed with Mary his espoused wife, being great with child.

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