WASHINGTON (AP) — U.S. services firms grew at a slower pace in April compared to the prior month, as companies are reporting cost pressures from possible tariffs and a shortage of available workers.

The Institute for Supply Management says its services index fell to 56.8, from 58.8 in March. This marks to lowest reading of the index this year. Still, any reading above 50 is a sign of expansion. The services sector has been expanding for the past 99 months, or more than eight years.

The index is drawn from a survey of purchasing managers in the services industry, which includes finance, health care and retail and accounts for the majority of U.S. economic activity. The employment and production components of the index decreased in April, although both pointed to continued growth.