The pace of factory activity in the U.S. mid-Atlantic region waned in April for the first time in five months as new orders fell to their lowest since September, a survey showed on Thursday.

The Philadelphia Federal Reserve Bank said its business activity index fell to 8.5 from 12.5 in March, worse than economists' expectations for a modest decline to 12.0, according to a Reuters poll. It was the lowest level since January.

New orders slipped to 2.7 from 3.3.

Any reading above zero indicates expansion in the region's manufacturing sector. The survey covers factories in eastern Pennsylvania, southern New Jersey and Delaware.

It is seen as one of the first monthly indicators of the health of U.S. manufacturing leading up to the national report by the Institute for Supply Management.