The Made in China label is losing traction with its two biggest customers. After three decades of gains, China's share of U.S. imports has plateaued and in Europe it's in decline.

The steepest losses are in the European Union, where China's share of imports slumped to 16.5 percent in the first 11 months of last year, from a 2010 high of 18.5 percent, according to data compiled by Bloomberg News. In the U.S. the needle has barely moved in the past five years, holding around 19 percent.

China's low-cost vantage has been blunted by rising wages and an appreciating currency, with cheaper nations including Vietnam and Bangladesh competing to sell products from T-shirts to shoes. With an unexpected drop in total exports in February compounding the challenges, the trends underscore the need for President Xi Jinping's government to foster competitiveness in higher-technology items from semiconductor chips to medical-imaging equipment to airplanes.