As part of the pre-approval process, lenders will pull your credit report. If your credit report is pulled more than three times within a 6-month period, this can lower your credit score. It’s therefore not advisable to obtain more than three mortgage pre-approvals within a 6-month period. A better option is to use a mortgage broker, who can compare mortgage rates across multiple Big Banks and other lenders so that you will only need to apply for a pre-approval once.