U.S. 30-year fixed-rate mortgage rates fell to a new record low of 3.89 percent in the week ending Jan. 12, according to Freddie Mac.

The 30-year rate has been below 4 percent for six consecutive weeks, reflecting record levels of home affordability. Rates fell from 3.91 percent in the previous week and 4.71 percent in the same period in 2011. But the drop came amid continued uncertainty in the labor market, as well as tighter underwriting standards by banks, that has made a recovery of the housing market elusive.

Mortgage rates eased slightly this week to all-time record lows following mixed indicators in the labor market. Although the economy added 1.6 million jobs in 2011, which was the most since 2006, the unemployment rate remained historically elevated, said Frank Nothaft, vice president and chief economist of Freddie Mac, in a statement. The 2009 to 2011 period had the highest three-year average unemployment rate since 1939 to 1941.

Fifteen-year fixed-rate mortgages average 3.16 percent, down from 3.23 in the previous week and 4.08 percent in the previous year.

Five-year Treasury-indexed adjustable-rate mortgages (ARMs) averaged 2.82 percent, down from 2.86 percent in the previous week and 3.72 in the previous month. One-year Treasury-indexed ARMs averaged 2.76 percent, down from 2.8 percent in the last week and 3.23 percent in the previous year.