NEW YORK: Millennial women shop differently for bras, wear a greater number of styles and buy them more often than other demographics, according to a new study which points to the influence of the "athleisure" industry on their behaviour.

The report from NPD Group – 2015 Bra Journey Insights – revealed that among consumers of all ages the great majority of purchases are planned, with the need for replacement usually the driver of action.

But Millennials, it said, start their engagement with the category differently.

"The comfort and wearability of the athleisure apparel trend that is embedded in the Millennial style vocabulary will compel them to seek the same type of comfort and ease of movement throughout their bra journey," said Marshal Cohen, NPD's chief industry analyst.

"This ultimately drives them toward different shopping behaviours than those of Boomers and older generations."

Sports brands such as Under Armour and Nike already offer a wide range – the latter boasting more than 25 sizes in some of its bras while also providing a detailed explanation of its bra technology.

But even with all those sizes, many women – as many as 80% in some surveys – struggle to find one that fits them well and is comfortable.

"Although their definitions of comfort may differ, Millennials and non-Millennials will buy more than one bra when they find the one that suits their lifestyle," Cohen noted.

And that also leads to the development of a strong brand loyalty. "The lifetime value of that customer is tremendous," according to Ani Collum, a partner and retail consultant at Retail Concepts, a Boston-based consulting company.

"The entire fashion industry is moving toward products that truly perform, and bras haven't kept up," she told MediaPost.

"Across the entire consumer landscape, innovation is everywhere, with an especially big interest in technology in apparel. This is a category that is ripe for disruption."

One company, Trusst Lingerie, is using 3D printing to develop a new design that supports breast weight from underneath rather than relying on shoulder straps.

Data sourced from NPD, MediaPost, Mashable; additional content by Warc staff