WASHINGTON — U.S. employers cut back sharply on hiring in September and added fewer jobs in July and August than previously thought — a sour note for a labor market that had been steadily improving.

The economy added just 142,000 jobs last month, depressed by job cuts by manufacturers and oil drillers. The unemployment rate stayed 5.1 percent, but only because many Americans have stopped looking for work and are no longer counted as unemployed. The proportion of adults either with a job or looking for one is at a 38-year low.

Today’s tepid jobs report from the government suggested that the U.S. economy, which has been outshining most others around the world, is weakening. Lackluster growth overseas has reduced exports of U.S. factory goods. China, the world’s second-largest economy after the United States, is slowing.

The dollar has risen about 15 percent against overseas currencies in the past year, making U.S. goods costlier overseas and imports less expensive. Lower exports likely helped hold growth in the July-September quarter to a meager 1.5 percent annual rate, according to economists from JPMorgan Chase. In addition, sharply lower oil prices have led U.S. drilling firms to lay off workers and slash spending on equipment.

The tepid pace of hiring complicates the picture for the Federal Reserve, which is considering whether to raise interest rates from record lows. Fed Chair Janet Yellen has said that the job market is nearly healed.

But she has also said she wants to see further hiring and pay growth to provide reassurance that inflation will move closer to the Fed’s target of 2 percent.

Average hourly wages slipped by a penny in September and have now risen by only 2.2 percent in the past year.

“Every aspect of the September jobs report was disappointing,” said Michelle Girard, an economist at RBS Securities. It “strengthens the case that the Fed will be forced to stay on hold over the remainder of the year.”