I cannot *believe* this was not already an answer.

## Speak to an employment attorney. ##

I am not a lawyer, but you have clearly been discriminated against for your pregnancy. If your pay was lowered, you also have demonstrable damages. Based on what you've said in your post, a lawyer can probably point out a whole lot more labor law violations too.

**Do not speak to HR**. If you intend to sue your company (you probably should, but again a lawyer can advise you better), their job is to protect the company from *you*. Even if you don't plan to sue your company, HR will be hesitant to take action against the *owner of the company* when they know there's a high chance they'll face retaliation, legal or not.

You may be afraid you're burning bridges. You're not; your manager cannot be relied upon to give you a good recomendation anyway (unless a court forces him to), and since you're competent, you can find a job with much better working conditions.