U.S. factory output was flat for the second straight month in January, raising questions about the manufacturing outlook as production dropped in the aerospace, plastics and food industries.

The lack of growth in U.S. manufacturing, reported on Thursday by the Federal Reserve, confounded analyst expectations for a 0.3 percent monthly gain. The Fed had previously estimated a small increase in output for December but revised the data to show no gain in that month.

Overall industrial production fell 0.1 percent in January, dragged down by a 1.0 percent decline in mining output. Utilities output rose 0.6 percent last month.

The industrial sector has received support over the last year from a strengthening global economy.

Manufacturing output last month was held back by output declines of 0.2 percent at aerospace factories, 0.5 percent for those producing plastics and 0.4 percent in food industries. Output rose modestly overall for goods made to last at least six months, with gains in production of primary metals, computers, and motor vehicles.

Capacity utilization, a measure of how fully industries are deploying their resources, fell to 77.5 percent.