AIBU to not tell work I'm pregnant yet?

[StillNoFuckingEyeDeer]

I started in my current job in January, on a one year contract. It will almost certainly be renewed. I'm part time and they advertised for another person to do the same job part time, so there would be two of us, but got no applicants. They're going to advertise again.
At the moment we are applying for contracts for work that will be ongoing for over a year. I will be very involved in this work. I'm not sure that it's completely dependent on me being there, but it could be. They would definitely need to find the second person for the role or my bosses would have to get involved to cover the work (which would be difficult, but not impossible - they can do it, but are very busy).
I'm currently 12 weeks pregnant. I don't want to say anything yet - I want to wait until after I get my new contract, so I know I actually have a job. But AIBU to not let them know that they can't depend on me for a full year when applying for these contracts?

Well, they can't depend on you for a full year regardless of whether you are pregnant. You might decline their offer to extend your contract. You might get six months in and decide you want a permanent position and leave. I don't think you have to tell them at all. Although you might royally piss them off depending on what they are like.

But if you do keep quiet will you feel under pressure to hide yr baby bump?

YANBU

Agree with LaLyra too (I'm learning a lot today!).

Them having you on a short term contract suits them. So you are doing what suits you. You don't owe them any more than that. They aren't doing you a favour by employing you.

I was in exactly your shoes OP and I didn't tell. I just kept wearing the same work suits with the top button undone until I had my new contract signed

Luckily for me, my boss saw the funny side and never held it against me so it all worked out for the best.

Don't tell them until after you have your contract. If they need to backfill your role whilst you are on mat leave, that's their problem. Look after number one. Most employers don't give a crap about their staff particularly temporary staff, and if they're not giving permanent contracts out what does that say about them? That's right, they don't really care too much about your needs. So don't be too concerned with theirs.

I told my boss even before the pee had time to dry.

Working in the role I do it was vital to protect my baby. Especially as I use buffers and go into areas that are highly infectious.

I would say only tell your boss if being pregnant could effect your Heath or the Heath of the baby.