I need opinions ladies.

I was just offered a position that I cannot turn down. I am currently 11 weeks pregnant and felt no need to bring it up during interviews ( I was only 7/8 weeks when they started ).

I’ll be 13+1 on my start date. Should I just tell my new boss then? My only concern is I am in a 90 probation period. It’s a management position, so pregnancy won’t effect my job performance. But I’m worried they’ll find some reason to let me go. I’ll be 27 weeks with my 2nd child at the end of my 90 days, so I there’s no way I can hide it (nor do I feel right to hide it that long!)

Has anyone had any experience in this circumstance?