‘ So Boaz took Ruth, and she became his wife, and he went in unto her, and YHWH gave her conception, and she bore a son.'
The consequence of what had happened was that Boaz took Ruth and she became his wife, and as a result of his having impregnated her ‘YHWH gave her conception', and she bore a son. This is the second time that it has been made clear that YHWH was with Ruth, and that the son to be born was of His doing (compare Ruth 4:12). It made clear that YHWH had accepted her, a Moabitess, as a true member of the covenant.