Rebecca Cutler and Jennifer Krane noticed that pregnant women had few choices for athletic wear. They discovered that 4 million babies are born every year in the U.S., and American women spend an estimated $1.2 billion annually on maternity wear. They came up with the idea that a box set of fashionable maternity athletic clothes that included a mix-and-match set of reversible tennis skirts, a few V-neck shirts, and shorts might sell. It did, and they expanded their line to tennis, golf and yoga clothing. Gross sales are projected to reach $1 million in 2004. Cutler and Krane jumped on a trend early, which helped them develop a loyal customer base even as the "big guys" are starting to catch on and compete with them.

Early trend spotting can set up young companies for long-term success. The hard part is discerning whether something is a long-lasting trend or a fad that will die out in six months.

What's the difference between the two? A fad is a statement, a one-hit wonder, something eye-catching that comes and then goes just as quickly. A trend has roots and staying power, it strikes a deeper cord and is connected to a larger change in society. One expert said a trend spans more than one industry and touches more than one market and generation. For example, the iPod, which satisfies our desire for more mobility, instant gratification and customization, and craving for all things fashionable.

It's too late to catch a trend if you're seeing it at a trade show. Cutler and Krane kept in touch with their customers by conducting focus groups and built momentum based on what they learned. Distinguishing between trends and fads requires quantitative and qualitative research in addition to gut instinct.

A partner in a marketing and design firm notes that every trend has a countertrend - for example, technology is becoming more pervasive as people are spending more money to go places where they can escape it. There is room for entrepreneurs who can take advantage of a countertrend by, for example, luring the coffee lover who is turned off by Starbucks.

Telling the difference between a fad and a trend is a constant balancing act for entrepreneurs. Staying in touch with the customer and testing innovations before making large commitments are key.