In Final Fantasy when did Ultimecia give birth to her son Sephiroth?

Ultimecia does not give birth to Sephiroth in the Final Fantasy series; this is a common misconception. Sephiroth is actually the son of Lucrecia Crescent and Hojo, a scientist from Shinra. Ultimecia is a powerful sorceress from Final Fantasy VIII and has no direct connection to Sephiroth, who is a character from Final Fantasy VII. Each character and their stories belong to separate narratives within the Final Fantasy franchise.