It sounds like you're already worried. That's legitimate. The good news is that your employer is probably liable for pregnancy discrimination if they fire you or "eliminate your position" in the near future. You should consider hiring a lawyer to develop a strategy to preserve evidence and create the strongest case possible in the event you lose your job.
-Alex J. Higgins
The good news is that you are still employed, collecting a salary and not terminated. Are the job duties that they have delegated to another or not given back to you, the type that if performed by you would ensure a promotion or increase in salary? Are the important things that they have you doing ministerial and insignificant and which would not be viewed as placing you in a higher rate of pay or promotion? Have you created a paper trail and expressed your concern in writing rather than just verbally? Draft letter expressing that nothing has been told to you as to why you are being excluded from important meetings and it is affecting not only how other employees perceive you but creating a concern for you. Remember that Washington State is an employee at will state and can fire and hire without giving you a reason. In order for it to constitute discrimination and/or retaliation, there must be a nexus between their acts and the fact that you are pregnant.
This answer is predicated on the facts provided in which the lawyer cannot confirm or verify. I do not represent you as we do not have an attorney-client relationship.