Corporate profits were bolstered in the first quarter by tax cuts enacted at the end of 2017, but the underlying trend showed some signs of strain.

A key measure of U.S. business earnings, profits after tax without inventory valuation and capital consumption adjustments, jumped a seasonally adjusted 7.8% in the first quarter after dropping 9.6% in the fourth quarter, the Commerce Department said Wednesday.

The swing reflected, at least in part, the impact of cutting the federal corporate tax rate to 21% from 35% starting Jan. 1, and potentially other tax-related changes. Pretax profits with adjustments declined modestly over the past two quarters.

“These always swing around a lot, and particularly when you’re changing taxes as much as we’ve seen,” said Paul Ashworth, chief U.S. economist at Capital Economics.

Wednesday’s report also included revised figures for U.S. economic growth during the first quarter. Gross domestic product—the dollar value of all goods and services produced in the U.S., adjusted for inflation—expanded at a 2.2% annual pace, down slightly from an earlier estimate.