Is it typical for an employee to continue to accrue sick and vacation time while on maternity leave?

It all depends on the company policy. You just can't suspend leave accruals for pregnant employees on leave while continuing to accrue for other employees on leave who are not pregnant. The company I was with in California where I managed the payroll operation, we continued leave for one month following the last day on paid status. After that, leave accruals were suspended until the employee returned to work.