How to Disable printing of unapproved Purchase Orders?

Currently users are able to print a Purchase Order in APM even when the Purchase Order document has not been Approved by all Approvers on the Route. I need to be able to control this option and allow printing of Purchase Orders ONLY after all Approvals have been completed.

If someone has had a similar need and found a solution, could you please help me?

Thanks.

Obed Stanly.