(Reuters) - Wall Street's main indexes opened lower on Wednesday as fresh worries over the health of the U.S. economy kept investors on the sidelines in the run-up to labor data.

The Dow Jones Industrial Average fell 64.87 points, or 0.16%, at the open to 40,872.06. The S&P 500 opened lower by 22.25 points, or 0.40%, at 5,506.68, while the Nasdaq Composite dropped 120.58 points, or 0.70%, to 17,015.71 at the opening bell.

(Reporting by Purvi Agarwal in Bengaluru; Editing by Sriraj Kalluvila)