Seeing as we are still waiting for Academics' Corner....thought I'd post here and hopefully get some traffic from academics waiting around for term to start 
Just got a BFP on a pregnancy test - hurrah - it's the first day of my missed period. Rough calculation indicates that due date is around 12 May.
So my question is: when did you tell your HoD about pregnancy? I know the general standard is 12 weeks, after the first scan etc. I have specialist teaching which runs in both semesters and is examined at the end of the year, as well as a very heavy teaching load in the 2nd semester (which runs from Feb-end May).
I don't, obviously, want to leave my students/department in the lurch, but nor do I know how the pregnancy will go, whether I will need/want to finish early. And of course I don't want to needlessly broadcast pregnancy in case anything goes wrong.
Advice/experience gratefully received! Especially from those eminent MNers who have served as HoDs and possibly managed situations like this before.