Taking a job in second trimester- can they refuse now they've offered me it?

[isthereanypoint]

I had a previous thread asking if there was any point going to a job interview at 21 weeks pregnant in which I said I'd tell them at the end of the interview that I was pregnant. The interview went terribly so I didn't tell them but I was offered it over the phone today and I accepted. I was in shock but I still didn't tell them. My contract begins 1st March and I'm due in May. 6 months probation. My question is how do I tell them now that I am pregnant and can they withdraw the offer (under a different reason of course) as I've no official contract yet? I imagine they'll be annoyed as I wasn't straightforward and I have no idea how to go about it now.

1. should I call or text and 2) I'm not too sure what to say? After reading some of the replies, I feel awful but I am desperate. I can't even offer to sort of say 'I feel terrible and completely understand if your decision has changed' as they can't legally say yes, can they?

Get a contract before you tell them, please. You're entitled to take time off for your baby and have a job to go back to. There's a few people I think are cheeky burgers but a jobless family due a baby and wanting to work- you're not one of them.

Do what you can for your new family. Get what you need.

ACAS are a very good professionally trained free employment helpline, worth calling if you need it.