Affiliate Marketing Secrets

Im currently 23weeks pregnant and work for a very large company in the UK. I have applied for a Marketing job which last 3months that never comes up in another area of the company that doesnt know im pregnant (but HR does). I want this job so bad and i believe i have a good shot of getting it. Everyone i have asked has told me that i should keep my pregnancy quiet due to discrimation against pregnant women. But i have gotten to know the department im apply for who have helped me out to get the job interview but i dont want to be dishonest as they have been so good to me. Should I tell them and risk not getting the job on the fact im pregnant or should i keep it a secret and if i manage to get the job then tell them?