Americans looking to buy a home are facing pressure to act as soon as possible, as the era of rock-bottom mortgage rates that have sustained the nation’s housing market since the recession could be coming to an end.

For years, many home buyers have enjoyed interest rates of under 4 percent, far lower than historic averages. But many analysts say that will change if the Federal Reserve begins pulling back its support for the American economy next month, as is widely expected. An increase in the central bank’s benchmark rate is likely to result in rate increases for all sorts of loans, particularly mortgages.

Already, rates have crept higher in anticipation of Fed action – and that is forcing both buyers and sellers to reevaluate their budgets and behaviors. Average rates on 30-year fixed-rate mortgages have climbed in recent weeks by about a quarter-percentage point, from 3.75 percent to almost 4 percent – about a $600-a-year difference on a $350,000 mortgage.

Several sources of data suggest that buyers are paying more attention to the threat of higher rates. The number of mortgage applications submitted this fall was about 20 percent higher compared with the same period a year ago, according to the Mortgage Bankers Association, an industry group. That could reflect the fact that more people are looking to buy even after the busy summer season.

But while some are moving more quickly to buy, others are feeling as though an opportunity may have passed.

Kradak Thomas, a 43-year-old chemist living in Potomac, Maryland, said he and his wife had recently considered moving their family to Virginia for a shorter commute. But moving from their home, where they have been for seven years, would have meant giving up a 3.25 percent mortgage rate.

The higher rates now mean they would need to find a less expensive, potentially smaller home in order to keep their monthly mortgage payment about the same. So they have decided to stay put.

“You add all of those things up and say, ‘Well, what’s that going to do for us as a family?’ ” Thomas said.

More than 90 percent of buyers in a recent Redfin survey cited low interest rates as motivation for purchasing a home.

The Mortgage Bankers Association expects that rates on 30-year loans could reach 4.8 percent by the end of next year, topping 5 percent in 2017. Rates haven’t been that high since the recession.