SHANGHAI - An egg bank, one of the first of its kind in China, will be created in the city to help women postpone pregnancy by having their eggs frozen for future use.

The egg bank, which comes at a time when more urban women are postponing pregnancy due to high work pressure and when infertility is increasing among the young, will be set up in three years, the Shanghai Morning Post reported on Friday, citing a plan by local health authority.

But the bank would primarily offer an ovum-freezing service to women who have been diagnosed with cancer, to be used before chemotherapy or surgery could harm their ovaries and eggs, said Di Wen, head of the obstetrics and gynaecology department of Shanghai Jiaotong University-affiliated Renji Hospital.

After having their healthy eggs frozen and stored, these women may have a chance to have babies in the future, he said.

An egg, which typically dies within 10 hours after being removed from the womb, can be preserved for at least a decade after being submerged in liquid nitrogen cooled to -196 C.

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The bank would also help to preserve eggs for women who give priority to career development when they are young and who are concerned that the quality of their eggs might deteriorate with the passage of time, he said.

Meanwhile, those with fertility problems may also realize their hopes of having a baby through donation of stored eggs.

The demand for egg-freezing technologies is on the rise but egg banks have been rare in China.

According to Di, although sperm-freezing technologies are quite advanced around the world, egg freezing is much more difficult and there have been fewer than 10 babies born successfully from frozen eggs in Shanghai.

Experts agree that the practice still faces many technological hurdles, such as the low success rate of impregnation after the frozen eggs are thawed. It is still not clear whether babies born from the technology are healthy or not.

There are also ethical concerns over whether one woman should be allowed to donate more than one egg in case babies born using eggs from the same woman would one day get married.

Shanghai established a sperm bank six years ago, where donated sperm could help men with infertility problems produce babies.

According to Li Zheng, director of Shanghai Sperm Bank, more and more men are suffering from infertility because of increased pollution and unhealthy lifestyles due to increased job pressure.

He said the number of couples wanting to have children through artificial insemination is on the rise, but the amount of donated sperm is not enough to meet demand.

Across China, an estimated 8 to 10 percent of the reproductive population are experiencing problems having children, said Li.