Even though most Chinese women are still too shy to talk about their menstrual cycles, a mobile application is doing just that.

Dayima, the Chinese term for a woman's period, is a mobile application for women's menstrual health. Its functions include keeping records of a woman's cycle, forecasting it, admini stering a self-test for premenstrual syndrome and advice.

Its founder is a 27-year-old man. Chai Ke chose the category on the advice of his parents, who are both medical professionals, and his fiancee, whose symptoms he observed during sensitive days.

The mobile app, online since 2012, has attracted 40 million registered users and investors Sequoia, Bertelsmann and Zhenfund. That's despite the fact that it has yet to make a profit.

Wang Qian, 32, of Beijing , has been using Dayima to track her menstrual cycle as she tries to get pregnant. "It has been accurate in predicting" ovulation dates, she said.

But Dayima is not the first product Chai's team has developed. Previous attempts at product development include applications to help users keep fit and lose weight and another to track diabetes. But none was popular.

"In the advanced information era, health is a behavior. But if information can't be translated into action, it is impossible to relate it with health," said Chai.

Compared with other health categories, a women's menstrual cycle is unique. "It is so simple but vital to every woman," he said.

"The investment in paying attention to one's menstrual cycle is little yet it comes with a high return," he said.

"If you download an application telling you to go jogging to lose some weight, but you don't run, there is nothing we can do about it. But there are few ways a woman can stop their period from coming every month."

The company has prioritized its key product instead of developing social networking products or games. "We need to focus," Chai said. The firm has hired 20 physicians to gather data and research algorithms and related information.

Chai's goal is to build a health and medical product by using menstrual cycle data so women can become healthier.

For instance, he has found that the average menstrual cycle in Chinese women has lengthened to 31 days instead of 28 days, which has been recorded for 2,500 years and still is widely recognized. "Women have evolved," he said. "It is a chance to redefine women through our data.

For example, their statistics can predict the next phase in a woman's reproductive life and even diagnose health risks, he said.

The potential market for female users of the application is mas sive. Wang Jian, an analyst from Analysys International, said female users on the mobile Internet have reached 250 million, and the number is growing.

Researching women has had an impact on Chai's views and actions towards the opposite sex. For example, female employees at Dayima, which takes half of the Internet company, have more benefits than their male colleagues. They get one paid day off during their period, meals and feminine hygiene products for free.

"I am more willing to listen to women and respect their needs on specific days with more understanding and respect," Chai said.