My wife works for a small veterinary clinic as a veterinary technician.  She averages around 30 hours per week there working 3-4 days per week.  

She is currently pregnant and gave them a doctors note saying she could not lift over 25 pounds during her pregnancy.  She planned on working through the majority of her pregnancy and then taking a couple months off to spend with our new son before returning to work.

Today they approached her and told her they would need to cut her hours to 1 day per week because they needed to hire someone who could lift all of the animals without concern for size.  They have no other reason to cut her hours and gave her no other reason.

They have been calling her the day of or the night before the last couple weeks and telling her not to come into work for different reasons.  Then this today.  

She has been very unhappy there for a while and in the heat of the moment told them they would receive her letter of resignation tomorrow.

What, if any, legal recourse do we have?  To me this sounds like they're openly discriminating against her because she's pregnant which I know is not ok.  So with all of that what should we do?  Thank you.

You'll need to talk to an employment lawyer.

http://www.scotusblog.com/2015/03/opinion-analysis-fashioning-a-remedy-for-pregnancy-bias/

Seems it could be a tough case based on that article, thank you.

Is SC a right to work State?  Consult a lawyer, have her sleep on it as far as quitting.

What does labor unions and being forced to join them have to do with the question?

Correction - SC being an at-will employment state, right to work is different.

Perhaps the Americans with Disability Act comes into play here? ADA requires "reasonable accommodations" and lifting heavy items during pregnancy IMNSHO (IANAL) should fall under this category.

Good luck.

I thought we were right to work

Right to Work just means you don't have to join a union to get a job.  It has nothing to do with your wife's situation.

The correct term is "At-Will Employment", which means either employee or employer can terminate the employment contract.

If your wife's hours were constructively cut down to zero then she needs to file for unemployment starting the week she wasn't given any hours.  She also should not submit a letter of resignation unless she doesn't want to receive unemployment.

She could have any number of claims depending on her tenure, the size of her employer, employer's policies, state law, etc.  Possible claims could include disability discrimination or failure to provide a reasonable accommodation, pregnancy and/or gender discrimination, or FMLA interference.  This is just a partial list of potential federal claims.  She may have additional rights under state law.  Go to http://exchange.nela.org/findalawyer and get a consultation with an employment attorney in SC.  NELA is the largest group of attorneys that represent employees.  

On the form I would check the boxes for FMLA, Title VII, Disability Rights, and Gender Discrimination.  

Also, disregard absolutely everything in this thread about being employed at-will or in a right to work state.  It has nothing to do with your situation.

Thank you