It sounds like this company is serious about knowing if you are pg.

While on the subject of discrimination, my old role included hiring people for data processing work and I work for a large government organisation. We had three temps on assignments and two were very emotional and needed time off quite regularly. The other was so big when she left that I had to support her when I walked her out on her last day.
When I interviewed the next temp she told me straight away that she was six months pg. Given the history on the other women, I did not want to risk it and almost didn't give her the job. Well, how wrong was I. She turned out to be the best temp we ever had and had no problems with her pg. She worked almost to the end and apart from her bump, you would never know she was pg. She was such a no fuss person who enjoyed her pg and her productivity was double to some others.

This was probably the one if the biggest lessons I have learned and apart from being against the law it is wrong.

So my advice is not to tell them, you never know when people (like me)may discriminate.

Gemma.