Huang Qian, a professor of economics and demographics at Nankai University in Tianjin, said the decline began in the 1990s.

"The employment rate for women age 25 and younger has declined drastically in recent decades, mainly because a growing number of them have access to higher education. Despite the decline, entering higher education has been a positive trend for women, providing them with wider career paths and more freedom to make choices," he said.

However, he said the universal second-child policy may lead to a steeper decline and have a negative effect on women's careers.

Dai Shujuan, a 33-year-old mother of two, spent three years as a homemaker after giving birth to her second child. She said taking care of two children took up much more time than looking after one child. Also, it was hard to ask for leave from her employer, a private company that was heavily focused on the efficiency of its staff members.

As a result, she quit her job and stayed home.

"When I was pregnant, the company was unhappy if I asked for time off to have health checks. Later, with two children to look after, life was like a guerrilla war. What's more, my work left me with little energy to spare for my family," she said.