A biochip developed by the National Engineering Research Center for Beijing Biochip Technology can evaluate the quality of sperms and eggs. Zou Hong / China Daily

Implantation screening

Many couples who need IVF technology, such as Li and her husband, say they don't just want a "test-tube" baby, but also a genetically healthy one.

"About 20 percent of infertile patients who want a baby have to turn to IVF. Since the process is more invasive and costly, we need to choose the best-fertilized eggs for implantation," said Qiao Jie, president of Peking University Third Hospital, where more than 5,000 test-tube babies were born last year.

About 10 eggs are fertilized simultaneously in the hospital's lab, according to Qiao. When the fertilized eggs developed into a blastula - a hollow sphere of cells - doctors choose one or more cells for genetic screening, a process known as pre-implantation genetic diagnosis. If a blastula passes screening, it will be placed on a waiting list for implantation.

Under the current procedure, eggs are kept in liquid and can swim freely, which makes it difficult to monitor them every day. However, on the biochip, each egg is positioned undamaged and the channels on the biochip allow the sperm to meet the egg naturally.

"The technology has not been tested on humans. But if it completes the clinical tests successfully, it will make future study of IVF technology far more convenient," Qiao said. "It follows the trend of 'precision medicine' - an approach that allows doctors and researchers to more accurately predict which treatments and prevention strategies for specific illnesses will work in which groups of people."

According to Xie, the next research program will focus on trying to build a biomimetic uterus, which can mimic biochemical processes and, therefore, support the growth of human embryos.

"It may even mean that in the future, a baby may be born without a mother. Human assisted-reproduction technology is moving forward rapidly, and that's expected to bring greater benefits to the next generation," she said.

Contact the writer at yangwanli@chinadaily.com.cn

Sperm counts on downward spiral

Average sperm counts in China have been falling for more than 60 years. In the 1940s, the average among healthy men was 130 million sperm per milliliter, but the number has fallen consistently since then, according to Jiang Hui, deputy director of the Center of Human-Assisted Reproductive Technologies.

"The decline in the sperm count has not just been witnessed in China, but in most countries," Jiang said, adding that the World Health Organization has updated the global standard of sperm counts. Under the WHO's standards, sperm counts of about 60 million per ml were considered normal in 1989, but by 2006, the number had fallen to 20 million. It's still falling.

"Now, it's 15 million," Jiang said, attributing the decline to a wide range of causes, including environmental pollution, lifestyle changes, people taking less exercise and increased work stress. A couple is considered to be infertile if there are no signs of pregnancy after a year of unprotected intercourse, according to Jiang.

He said 40 percent of infertility cases are due to problems with men, and 40 percent due to problems with women. The causes of the remaining 20 percent are unknown.

Evaluation of the male factor involves a semen analysis, a post-coital test (conducted 6 to 12 hours after intercourse to detect the presence of sperm in the woman's cervical mucus) and hormonal determinations of the level of testosterone.

A normal semen analysis requires a volume of 2-to-5 ml, and the semen is considered to be healthy if it shows more than 15 million sperm per ml and they have a mobility range of more than 50 percent.