Those who are mentally of psychologically ill or disabled, namely, those who cannot take responsibility for care of children, are exempt from the mitzva to procreate. We can infer from the idea that marriage can be delayed until a man’s worldview and ability to provide for a family stabilize (5:7 and 5:9 above) that one who is incapable of taking responsibility for the care of his children, even at the most basic level, is not obligated in the mitzva. Even if such a person is capable of marrying, the couple should avoid having children. The easiest method is via an IUD.[5]
[5]. R. Auerbach writes that one who is unable to raise children is exempt from the mitzva to procreate, unlike a mamzer and one who is half-slave and half-free, who are mentally fit. If a man with such an illness seeks help to enable him and his wife to have children, he must be told that because he cannot care for children, he is exempt due to circumstances beyond his control (Minḥat Shlomo 3:103:2). In my humble opinion, since they are not obligated to procreate, they must use contraception, so as not to bring a child into a family that cannot care for it properly. I recommend above that they use an IUD, as it provides ongoing contraception without having to remember to do anything. If a grandparent is willing and able to take full responsibility for the child’s care and wants the couple to have a child, they are not obligated to use contraception.
