Benefits for maternity leave are the same as for any other medical malady. Once again, the policy manual probably covers this. But think of it this way: If you knew that you were going to have an operation of some kind, what would your leave eligibility be? If you were full-time, you would most likely be entitled to be off work as long as your primary physician said you needed to be; and your job or one very much like it would be waiting for you upon your return.
Again, if you were full-time, your company may offer short-term disability and/or long-term disability for such situations; and the FMLA (Family Medical Leave Act) would apply. However, if you are part-time, you may not qualify for either of these. Often disability insurance programs are for full-time employees only; and the FMLA requires that you work a minimum of 1,250 hours during the 12 months before requesting the leave.