Should I have children despite my health conditions and advanced age, or should I reject my husband's desire, given that he is threatening to marry another woman?

If pregnancy would cause the wife excessive harm or unbearable hardship, based on the report of a trustworthy doctor or conclusive experience, then she is not obligated to obey her husband's request [to conceive]. The husband, however, has the right to marry a second wife. The husband is advised to care for the upbringing of his children and not to marry a second wife unless he is financially capable, able to be just, and feels a need for it. The wife is advised to obey her husband if pregnancy would not cause her extreme hardship. Marital life is based on understanding and affection.