Torchwood (2006)

S2E9 Something Borrowed

On her wedding day, Gwen discovers that she is pregnant with the child of a shape-shifting alien male. As the alien’s life-partner becomes determined to reclaim its mate, putting Gwen’s life in jeopardy, the team scrambles to reach her. Meanwhile, Gwen remains resolute about proceeding with her wedding in a remote setting, surrounded by her family.