Tang Zhou and his wife are planning to have their second child, a test-tube baby. His wife had a natural delivery when she was 34 and their first child, a boy, is now 7. The couple are now hoping to have a daughter through _ in the US. "My wife couldn't bear another delivery because of her heart condition and her age. Surrogacy helps avoid the risks to older mothers," Tang said, "Moreover, our second child will be born in the US and become a citizen there. That is not a bad choice." The couple spent weeks researching their move, looking for a reliable agency that provides surrogacy services overseas. Surrogacy is still illegal in many countries, including China. "We will be taking much higher risks by relying on a surrogate mother in China because we are not protected by any regulation or law. You pay a lot of money but may meet with many problems," Tang said. "You might not even get your baby back." Tang and his wife are part of an increasing number of Chinese couples who are turning to surrogacy services. Tang also considered surrogacy in Thailand but dropped the idea after recent reports about a baby with Down Syndrome  who was delivered through surrogacy and said to have been deserted in Thailand by the biological parents from Australia. Instead, Tang chose the California Surrogacy Center agency as his first option after reading the detailed introduction on its website. Compared with many other agencies that he could contact only via e-mail, the center has a consulting office in Beijing, Tang said. The center is in San Diego, California, and has satellite offices in Los Angeles and Beijing. According to Liu, the center has been operating for more than eight years, and about 100 surrogate mothers live in California. A surrogate mother refers to a mother who   _  .
acts as a baby-sitter nurses another woman's baby offers service to a new mother gives birth to a baby for another woman