While Hiragana and Hangul were considered “women’s scripts”, nobody actively prevented the men from using the script as well, and eventually the men came around. However, in China, women were actively prevented from learning Chinese script, so they went underground and developed their own script. They actively hid it from the men, which had the effect of preventing the men from learning it. The women hid it so well, in fact, that the outside world did not learn about it until 1983.
The script is clearly derived from Chinese script, but clearly different. The characters are half-width, with significant simplifications. More than that, however, is that only about 100 characters are logograms; the other characters are syllabic.
Some of the changes in the script have the effect — deliberately or not — of making it easier to embroider.
Alas, the last “native writers” of Nushu died recently. That, plus the secretive nature of the script, mean that little is known of its history. There isn’t even agreement on how many characters there are in the script: estimates vary from 600 to 1500. This makes it difficult to date, but some of the simplifications in the script, are similar to simplifications common in Chinese script since the 1300s, so scholars feel it cannot be from earlier than then.
Recent documentaries and a popular novel featuring Nushu have led to a mini-revival, although there is concern that it will be distorted by tourism.