And it seems that God wanted to teach and attest that the begetting of children is wonderfully pleasing to Him, in order that we might realize that He upholds and defends His Word when He says: “Be fruitful.” He is not hostile to children, as we are. Many of us do not seek to have offspring. But God emphasizes His Word to such an extent that He sometimes gives offspring even to those who do not desire it, yes, even hate it. Occasionally, of course, He does not give it to some who earnestly desire it. It is His purpose to test them. And, what is more, He seems to emphasize procreation to such an extent that children are born even to adulterers and fornicators contrary to their wish.

-Luther, AE 3