As with any large purchase, your credit report will be pulled and reviewed by the mortgage lender. 

The main advantage of why government mortgages are so attractive is that the lender is not required to judge your credit by the numerical score alone.  Many of the guidelines of "Government" mortgages may be somewhat more relaxed.

Typically they are looking at your present rental or mortgage payment history first.  Then they will check for how many recent trade lines (credit accounts) that you have open or had within the last 12-24 months.  Ideally, 2-3 open trade lines with a recent payment history of at least 6-12 months would work. 

Sometimes you may be able to add a trade line (up to 3) that are not on your credit report for their review.  Items that you pay for regularly such as daycare or rental center items, or even in some cases, utility bill payments made on a monthly basis!