Death and taxes and childbirth! There’s never any convenient time for any of them.

The line wryly groups three inevitabilities—death, taxes, and childbirth—and rejects the comforting idea that life’s major upheavals can be neatly scheduled. Its humor comes from treating childbirth (often celebrated) with the same blunt fatalism as death and taxes, emphasizing how disruptive even “good” events can be. The sentiment points to a pragmatic, unsentimental worldview: waiting for perfect conditions is futile, because the most consequential experiences arrive on their own timetable. As a piece of dialogue, it also characterizes the speaker as sardonic and clear-eyed, using wit to manage anxiety about forces beyond personal control.