What episode does piper and Leo make Christopher?

Piper and Leo conceive their son Christopher in "The Seven Year Witch," which is the 14th episode of Season 6 of Charmed. In this episode, they face various challenges, including a time loop and the impact of a powerful witch. Christopher is later born in the Season 6 finale, "It's a Bad, Bad, Bad, Bad World," which showcases the culmination of their struggles and the joy of welcoming their second child.