But if thou hast gone aside to another instead of thy husband, and if thou be defiled, and some man have lain with thee beside thine husband: Then the priest shall charge the woman with an oath of cursing, and the priest shall say unto the woman, The LORD make thee a curse and an oath among thy people, when the LORD doth make thy thigh to rot, and thy belly to swell;...

If a wife was found guilty, the punishment was death (Leviticus 20:10). If the wife was found innocent, she would be “cleared of guilt” and “able to have children” (Numbers 5:28). So Numbers 5:11-31 does not refer to abortion in any sense. Rather, it is describing a method that God allowed to be used to determine if a wife had committed adultery against her husband.