I can't speak with any authority on this because sex education is relegated to the K-12 system. However, anecdotally, my experience is that this varies not only by state, but by individual school districts. I, for one, never had sex education despite attending a fairly progressive district. Instead, I learned about the male and female reproductive systems. Not how they're used or how to prevent infections/pregnancy. These omissions are not overtly couched in religion, but that's the root cause of it.