The new regulations involve a stress test for all insured mortgage applications to ensure the borrower can still service their loan in the event interest rates rise or their personal financial situation changes.
Before today, all insured mortgages with a term of 5 or less years and / or a variable rate mortgage had to quality using the Bank of Canada rate. With the new regulations, all insured mortgages regardless of term will have to qualify on Bank of Canada rate. Using this rate (usually is higher than what the market rate is), a lender will determine how much you can borrow and qualify for.
Bank of Canada rate is referred as the rate published by Bank of Canada for a Conventional mortgage on a 5-year term ( http://www.bankofcanada.ca/rates/daily-digest/ ).
The new regulations will impact first-time home buyer's purchasing power, however, each mortgage is different for each buyer, therefore, the new regulations will have different impacts on individual mortgage situation.