Not all women in China dress like this, and that's not even what they're called. They're called chèuhngsàam (長衫; pronounced cheongsam) in Cantonese, zǎnze (zansae) in Shanghai, or qípáo (旗袍; ch'i-p'ao) in Mandarin.
In English, it's known as, "The Mandarin Gown". As noticeable as they are, no one (at least in the U.S.) really knows what they are called.