Ovarian resequencing is a medical process in which incompatable gametes are modified to allow conception.
In 2374, Jadzia Dax read an article on interspecies conception and theorized that Jem'Hadar DNA could be altered in a similar way and make them less aggressive. (DS9 - Prophecy and Change short story: "The Devil You Know")
Later that year, Julian Bashir began giving Dax ovarian resequencing enzymes to allow her and Worf to have a child. The enzymes had begun to work before Jadzia was killed by Dukat. (DS9 episode: "Tears of the Prophets")