What to call naive pregnancy?

Hi, I’m not sure if I can ask questions here but I haven’t found a subreddit just based on looking for info on erotica.

I have tried searching for this general scenario:

Couple lack sex education, don’t know how pregnancy happens, have sex following their base instincts not realising consequences.

I’ve mainly searched ao3 as they have an extensive tag system, but I can’t seem to find the right term, sexual innocence, naive etc.

Does anyone know what this would be called?