WASHINGTON (AP) -- A measure of hiring by U.S. companies has fallen to a seven-year low and fewer employers are raising pay, a business survey found.

Just one-fifth of the economists surveyed by the National Association for Business Economics said their companies have added to their workforces in the past three months. That is down from one-third in July. Job totals were unchanged at 69% of companies, up from 57% in July. A broad measure of job gains in the survey fell to its lowest level since October 2012.

The hiring slowdown comes as more businesses are reporting slower growth of sales and profits. Business economists also expect the economy's growth to slow in the coming year, partly because tariffs have raised prices and cut into sales for many firms.

"The U.S. economy appears to be slowing, and respondents expect still slower growth over the next 12 months," said Constance Hunter, NABE president and chief economist at the accounting firm KPMG.

Hiring may also be slowing because the unemployment rate is at a 50-year low of 3.5%, and many companies are struggling to find enough workers. The survey found that 43% of companies reported shortages of skilled workers, though that figure has declined for three straight surveys. Government data shows that companies are posting fewer available jobs, suggesting that demand for labor is weakening, as well as supply.

Perhaps because of concerns over a weakening economy, businesses are less likely to offer higher pay, even with unemployment at a 50-year low. Just one-third of economists said their firms had lifted pay in the past three months, down from more than half a year ago.

Companies are also cutting back on their investments in machinery, computers, and other equipment. The proportion of firms increasing their spending on such goods is at its lowest level in five years, the survey found.

Sales are also growing more slowly. Just 39% of economists said they rose in the past three months, down from 61% a year earlier. And only 38% said they expect sales to rise in the next three months, also down from 61% a year ago.

Many business economists blamed President Trump's tariffs on steel, aluminum, and on most imports from China for worsening business conditions. Thirty-five percent said the duties have hurt their companies, while just 7% said they had a positive effect.

Of those who said tariffs had impacted their companies, 19% said they had lowered their sales and 30% said the duties pushed up costs.

That has cut into profits for many firms. Just 19% of economists said their companies' profit margins have risen in the past three months, barely half the 37% who reported greater profits a year earlier.

Two-thirds of the economists surveyed now forecast that the economy will grow just 1.1% to 2% from the third quarter of 2019 through the third quarter of 2020. A year ago, they were more bullish: Nearly three-quarters forecast growth of 2.1% to 3% from the third quarter of 2018 through the third quarter of 2019.

The NABE surveyed 101 economists at companies and trade associations from Sept. 26 through Oct. 14.