In Revolutionary Girl Utena, what is the metaphor of Nanami's egg? Ikuhara had said it would be better if we didn't know, but I want to know. What is the meaning behind Nanami's egg? Especially when she wakes up from an apparent dream, and finds a smashed egg in her bedsheets.
That episode was . . . weird, as weird as when Nanami became a cow.

Anyway, my interpretation of it was based on the fact that the episode "Nanami's Egg" falls into the Akio Ohtori Saga. This is roughly two thirds of the Apocalypse Saga. The content is more sexually suggestive in this saga: scenes involving Akio's car seemed to always be sexually suggestive, with his, Touga's and Kyouichi's shirts opening partway through the ride or when posing for photos, and Kozue's first sexual experience was in the back of that car with Ruka Tsuchiya.

Because of this I got the impression that the episode represented Nanami entering puberty as we  know that women to begin produce eggs during puberty. She begins to fret over the discovery of an egg in her bed probably because she hasn't been taught about puberty. When she accepts it and raises the egg, I took this as the transition of Nanami growing up from a girl to a woman/mother.