WASHINGTON — U.S. employers added 169,000 jobs in August and many fewer in July than previously thought. Hiring has slowed from the start of the year and could complicate the Federal Reserve’s decision this month on whether to reduce its bond purchases — and, if so, by how much.

The Labor Department said Friday that the unemployment rate dropped to 7.3 percent, the lowest in nearly five years. But it fell because more Americans stopped looking for work and were no longer counted as unemployed. The proportion of Americans working or looking for work reached its lowest point in 35 years.

The revised job growth for June and July shrank the gain for those months by a combined 74,000. July’s gain is now estimated at 104,000 — the fewest in more than a year and down from the previous estimate of 162,000. June’s figure was revised to 172,000 from 188,000.

Employers have added an average of just 148,000 jobs in the past three months — the weakest three-month stretch in a year. The average monthly job gain for 2013 so far is 180,000, almost identical to the 183,000 average for 2012.

Dow Jones industrial average stock futures rose modestly after the report was released at 8:30 a.m. Eastern time. The yield on the 10-year Treasury note fell to 2.87 percent, from 2.95 percent. Investors may think the jobs report makes it less likely the Fed will significantly slow its bond purchases after it meets Sept. 17-18.

The Fed’s $85 billion a month in Treasury and mortgage bond purchases have helped keep home-loan and other borrowing rates ultra-low to try to encourage consumers and businesses to borrow and spend more.

Friday’s report “is a mixed bag that can be used to support an immediate tapering of the Fed’s monthly asset purchases or delaying that move until later this year,” said Paul Ashworth, an economist at Capital Economics, said.