Employers cannot base employment decisions on assumptions about pregnant women's capabilities and health concerns.
Kindly let your employer know that you are still able to work effectively and do not wish to take your maternity leave just yet. If they continue, you should consider speaking with an experienced attorney, because the laws related to maternity leave differ on a state-by-state basis.
An employer may not compel an employee to take leave because she is pregnant, as long as she is able to preform her job. Such an act violates Title VII, even if the employer believes it is acting in the employee's best interest. Pregnant employees must be permitted to work as long as they are able to perform their jobs. If you have been absent from work as a result of pregnancy-related condition and you recover, your employer may not require you to remain on leave until the baby's birth. Also, an employer may not have a rule preventing you from returning to work for a predetermined length of time after childbirth. For example, a boss cannot deny a pregnant woman a promotion, assuming once she returns to work after childbirth she will be less committed to her job. Employers also cannot assign workers to less desirable jobs, even temporarily, due to concerns about pregnancy.