The two Sahih collections likewise relate that “al-Sa'b ibn Jathāmah asked the Prophet—may Allah bless him and grant him peace—about the inhabitants of a polytheist settlement who were raided at night, resulting in casualties among their children. He replied, ‘They are of them.’” (1)
If a woman (2), while pregnant, were to attack inviolable lives and property, and her assault could not be repelled except by killing her (3), she would be killed even if her fetus were also killed.
Thus, if it is assumed that Umar ibn al-Khattāb—may Allah be pleased with him—believed that enforcing the prescribed penalties fell under this principle, until it became clear to him that it did not (4), this would be no graver than the fighting at the Battle of the Camel and Siffīn, which led to forms of harm graver than this. Despite his careful judgment and independent reasoning, Ali—may Allah be pleased with him—did not expect matters to reach the point they did. Had he known, he would not have done what he did, as he himself stated.