An employee (pregrant) brings in an excuse from a Doctor stating she can only no more than 4 hours a day, 5 days a week and the employee wants to work more hours then the doctor recommends. Do we have to take the Doctors excuse or can the employee m

An employee (pregrant) brings in an excuse from a Doctor stating she can only no more than 4 hours a day, 5 days a week and the employee wants to work more hours then the doctor recommends. Do we have to take the Doctors excuse or can the employee make up her own mind as to what she wants to do...is the company liable for anything if something happens and she wanted to do this, or do I get something in writing from the employee stating she is not following the doctors advise? Please help.