No.  The Massachusetts Maternity Leave Act (See MA General Laws Chapter 149, Section 105D) requires your employer to put you back in essentially the same position you were in before.  Your employer can change your job but the new position must have the same pay and status as your prior position.  Clearly there may be some debate about the status requirement, so, when a complaint is filed, the MA Commission Against Discrimination will consider all factors, including the title of the new job, who you report to, your responsibilities, and any other relevant factors.  For your information, I have reprinted below 804 Code of Massachusetts Regulations 3.01(8)(c) and (d), which spels out the rights and obligation of the employee and employer upon the completion of the maternity leave.  Good luck, and for more information or to post a question, visit our MA Employment Law Discussion Forum.

(c) Rights of a Maternity Leave Employee to Return to Employment. If a female employee is eligible for maternity leave, as set forth above in 804 CMR 3.01(8)(b), she shall

1. be restored to her previous, or similar, position with the same status, pay, length of service credit and seniority, wherever applicable, as of the date of her leave, and

2. such maternity leave shall not affect her right to receive vacation time, sick leave, bonuses, advancement, seniority, length of service credit, benefits, plans or programs for which she was eligible, wherever applicable, at the date of her leave; and

3. such maternity leave shall not affect her right to be included in any system of accruing seniority or accruing benefits, if such benefits would accrue while an employee is on leave for sickness, disability or any other leaves. In all such cases, when such employee returns, her seniority date will remain the same as it was prior to her maternity leave.

(d) Rights of the Employer. An employer is not required to:

1. pay a female employee on maternity leave, such payment is at the discretion of the employer; or

2. restore an employee on maternity leave to her previous position, or similar position, if other employees of equal length of service credit and status in the same or similar position have been laid off due to economic conditions or other changes in operating conditions affecting employment during the period of such maternity leave. Notwithstanding the previous sentence, the employee on maternity leave shall retain any preferential consideration for another position to which she may be entitled as of the date of her leave; or

3. include the maternity leave of a female employee in the computation of benefits, rights, and advantages incident to her employment position; or

4. provide for the cost of any benefits, plans, or programs during the period of maternity leave unless such employer so provides for all employees on leave of absence.