"This is a common occurrence. Whilst I agree with your sentiment (that discrimination is not acceptable), your example is disappointingly ignorant"
And your reading comprehension skills are disappointingly poor.
I've been working in HR for 20 years, so steady on before you call me ignorant about employment issues, thanks very much.
I disagree completely that it's a 'common occurrence' for employers to withdraw offers because of a lack of honesty about a completely irrelevant disability. I've never come across that. Plenty of employers withdraw offers unlawfully because of the disability, absolutely. But not because of the lack of honesty.
This employer is (now) saying they have no problem with the pregnancy, only with the 'lack of honesty' about it. If you actually think that's the genuine reason you're incredibly naïve.
'Lack of honesty' is never the issue, with pregnancy, disability or anything else. It's the protected characteristic itself which is the concern. This employer is citing the 'honesty' and saying that if the OP had told them at the start of the process rather than just after the interview, it would have been fine. There's no credibility to that argument at all in my view.
Pregnancy is in my experience the only protected characteristic where both employers and often employees, feel there is some kind of moral obligation for women to be 'upfront' about it. You see it on these boards time and time again, people agonising about whether to tell, people being outraged (as some on this thread are) at someone even considering not being 'honest' about something which a prospective employer is not allowed to take into account anyway!
If they are not allowed to take it into account, what is the benefit in telling them? No one who argues in favour of honesty is able to explain this on these threads. All the OP would have been doing would have been burdening them with a 'big' piece of information they would not be allowed to do anything with. It's better for both the employer and the employee for the recruiting manager to be given the opportunity to make a decision about candidates without that information looming over them. That way everyone knows there was no discrimination.
I'd bet most of the people on this thread saying the OP should have been 'honest' about her pregnancy would not give the same advice to someone who didn't happen to mention a completely irrelevant disability at an interview.