If you have a large company there should be a "vertrouwens persoon" in the netherlands.
Talk to that person to see what they say about what is going on...
If you happen to live in Belgium, go to your union. They will help you as well in those type of situations.
But, first of all; talk to them. Maybe they havenīt realized yet what they are doing? Or that you know what they are doing. Give them a chance to become better persons.
I would not suggest leaving. Why would you let them win? You did nothing to be ashamed about.
There are laws against this, and in the Netherlands they are followed up pretty closely. So you have rights, and you can even go above your boss's head to see what is going on..?
Anyway.. congrats on your pregnancy, and good luck with you boss!