Manufacturing growth slowed in October from the previous month, a troubling sign that factories are struggling in the weak economy.

The Institute for Supply Management says its manufacturing index dropped to 50.8, down from 51.6 in September. Any reading above 50 indicates expansion.

Measures of production and exports fell and a gauge of employment dipped. On a positive note, survey respondents say raw materials prices fell sharply.

Factories were among the first businesses to start growing after the recession officially ended in June 2009. The manufacturing sector has grown for 27 straight months, according to the index.

However, factory activity slowed this spring, contributing to worries that the U.S. could be at risk of another recession.