Through prayer and fasting....Think for a second, before the anointed time (He who reads let him/understand ;-)), I am convinced they used to first pray to God for a miracle, this went on for years.
And guess what? That was a spiritual birth and if you see the lives of the kids Isaac, Samuel, Samson, John the Baptist and Jesus, they were zealous because the spirit of God was present during the baby making process.
During baby-making the Spirit of God is important, and folks who are trying should make sure they pray before and even during the process for the Lord knows the best swimmers which will lead to the development of a Jeremiah, Isaac, Samuel, Samson, Joseph, Ezra, Nehemiah, Daniel, Hananiah, Mishael, Azariah, Deborah etc.
The bible clearly states as does Jesus that death and being unfaithful to your partner is the only and i mean only reason you should divorce. If you divorce for any other reason you are committing adultry and forcing others to commit adultry that you lay or marry with.