How bad is this? (work related)

lpichach

So I started working for the company I am currently at last February (so I'm just about a year). When I originally got hired, I was told I'd be working on a similar position to what I had done at my other company because no one at this company has any clue about it!

However, with the title not reflecting that role I basically got pushed on to other work and have been trying to do it, but usually get pushed from my managers to focus on "the new role".  Since october they have been trying to create the role I was told I would do, and FINALLY are going to switch me starting Jan 1st. 

No one at work knows I'm pregnant.  Is it really bad of me to take this position knowing I'm only going to be able to do it for 6 months (due in june)?  I think it's okay since if i don't get the position because of this, that's discrimination righht? I just feel really nervous about telling them "the news" in the new year once i'm in the position... i mean, I can get a lot done in 6 months, but still.... is it really bad of me?