Media playback is unsupported on your device Media caption Chinese woman's 6,000-mile egg freezing journey

In China, there is a growing rank of unmarried women who are choosing to freeze their eggs overseas. These women are educated, middle class and often opt for a single life. They are the hallmarks of fast-changing Chinese society. But Chinese laws have not caught up, as the BBC's Grace Tsoi reports.

The rise of "singledom" is a worldwide trend and China is no exception. China replaced its one-child policy with a universal two-child policy in 2015, but it is also witnessing the rise of a female workforce that wants to focus on their careers and postpone starting a family.

An increasing number of Chinese women see egg freezing as a solution that could allow them to have it all. But the Chinese government forbids unmarried women from freezing their eggs, and there are still significant restrictions on fertility treatments.

Image copyright Getty Images Image caption Thanks to China's economic growth, Chinese women are now able to travel and enjoy the world

"I am not sure whether I want to have children. But I can afford the time and expense of egg freezing, so I want to give myself a choice in the future," said a 40-year-old woman living in Beijing , who only wanted to be known as ZZ. She froze her eggs in Los Angeles in January.

The explosive growth of the Chinese economy has allowed urban Chinese women an entirely different life and income bracket from their mothers and grandmothers. They can craft a career of their choice, accumulate wealth and enjoy pleasures like international travel. This is the first generation to have such benefits and they are acutely aware of it and want to maximise it.

"I can control everything in my life and I am happy with my independence."

A marketing manager in a foreign company, ZZ is also a fine art aficionado with a passion for painting and movies. She keenly feels her right to enjoy such luxuries.

For these women, egg freezing is a form of insurance. They may not necessarily use the stored eggs, but it gives them a shot at family life later down the line.

Career advancement

For the career-minded, egg freezing buys them time to pursue their professional goals.

Image copyright Getty Images Image caption Looking for a suitable partner is no easy task in Chinese cities

Jia, 26, doesn't have a boyfriend at the moment but she is planning to freeze her eggs in two or three years if she hasn't met Mr Right by then. "Even if I have a boyfriend, I won't get married until I am 30 or older."

"Career is an important part of life," said Jia, who will be pursuing a PhD degree in the United States. "I need to make sure my income reaches a certain level…I hope that I will be teaching at universities [after obtaining my PhD]."

Some Chinese women have their eggs frozen overseas to extend their fertility window, nursing the hope that they will meet and marry the right person in the future.

Describing herself as traditional, Ms Zhang, 40, has longed for years to find a husband and start a family of her own.

Image copyright Getty Images Image caption Worried parents place advertising notices for their single children at a "marriage market" in Shanghai

"It is difficult to find a suitable partner… Men are looking for younger women because they want to have children." She first froze her eggs in Taiwan two years ago, and she has undergone the procedure multiple times.

Ms Zhang believes women now encounter more difficulties looking for a suitable husband.

"China has undergone tremendous changes. After the Chinese economic reform [in 1978], it has led to great income disparity."

"In the past, everyone had similar income and social status. My parents' generation did not need to buy houses because they would be allocated housing by the work units," Zhang said. "[So] they would not take factors like education level into consideration [when choosing a spouse]… Their social circles were smaller… and they were more parochial."

She feels the ability to freeze her eggs has bought her some crucial time, but she could not have done this in China.

Chinese women also face additional pressure from Chinese culture, where extending the bloodline is sometimes considered a moral responsibility.

"By freezing my eggs, I can show my parents that I will eventually have children, just that I am focusing on other priorities now," Manman, a 31-year-old photography studio owner based in Beijing. Her eggs are now stored in Los Angeles.

Choosing egg freezing over adoption says a lot about the rootedness of the concept of bloodline, even among Chinese women, according to Tiantian Chen, who studies egg freezing practices among Chinese women.

Image copyright Getty Images Image caption Many Chinese people, especially the older generation, believe it is necessary to extend the bloodline

It is difficult to estimate the number of Chinese women freezing their eggs overseas, but it is an active topic on social media. There is a WeChat group advising unmarried women how to have children through unconventional means including egg freezing. Fertility agencies and clinics have already sensed the market potential.

"This is a growing business area," said Sammi Kwok, chief operations officer of Fertility & Surgical Associates of California.

In recent years, about 25 Chinese women freeze their eggs at Fertility & Surgical Associates of California every year. Kwok added that the number rises annually. But egg freezing will remain a niche treatment because of its price tag.

Although it is available in places like Taiwan and Cambodia, the US remains the destination of choice. Freezing one's eggs in the US costs about $15,000 (£11,400) to 20,000 (£16,000), excluding flights and accommodation. A storage fee is also needed.

Single women excluded

The availability of egg freezing technology remained unknown to the majority of the Chinese population until 2015, when A-list actress Xu Jinglei told the press that she had frozen her eggs in the US.

Later, state broadcaster CCTV reported that single women were not allowed to freeze their eggs, causing uproar on social media.

Under the regulation by China's National Health and Family Planning Commission, all assisted reproductive technology, including egg-freezing, cannot be used by single women.

Image copyright China News Service Image caption There are more than 20 sperm banks in China, but there is no egg bank in the country

Even married women face a lot of restrictions if they want to freeze their eggs in China.

According to Xinhua, hospitals will only store the eggs of married women under two circumstances: they are suffering from infertility and undergoing IVF treatment, or they are cancer patients before chemotherapy.

Similar restrictions are not applied to men if they want to freeze their sperm.

The regulation states that men are allowed to freeze their sperm as a form of "fertility insurance". It does not look at their marital status, or general health.

Family planning policy

"[Banning single women from freezing their eggs] has a lot to do with the family planning policy," said Chen Yaya, vice secretary of gender and development centre of Shanghai Academy of Social Sciences.

Image copyright Getty Images Image caption Single women are not allowed to have children of their own in China - unless they pay a fine

Marriage is a prerequisite to giving birth under China's family planning policy.

In most provinces, one of the unmarried parents is obliged to pay a fine called social support fee - but in most cases the burden falls upon the mother; children born out of wedlock also face trouble obtaining "hukou", the household registration document.

Women's rights activist Xiao Meili believes that part of the reason for the egg freezing ban on single women is to stop them from having children of their own.

"There must be a man [in a family]. The policy is a clear indicator of patriarchy in China."

Take back control

Image copyright BBC Chinese Image caption Some believe the Chinese government will allow Chinese women to freeze their eggs in the future

Chinese women's bodies have been subjected to stringent strict control by the state ever since the birth control policy came in place in the 1970s.

Even though such laws represent another form of state control over women's bodies, many of those who opted for egg freezing have a pragmatic attitude.

"Not allowing single women freeze their eggs is [motivated by] archaic ideas, but I am not radical enough to stand up and oppose the regulation," ZZ said.

"I managed [to freeze my eggs] using other ways. But I think the situation will change in the future."