I've found the conversation, and an article about the scent of 2nd stage (most midwives describing it as smelling like sex) but I cannot post the links here as they are to sites with forums.

I would imagine if you have a sensitive nose, that you are indeed smelling something that is indicating hormone changes. However I wouldn't go so far as to say this will likely mean labour soon, as we all know pre-labour (and hence the accompanying smells) can last for several weeks.