SHANGHAI — What can $1,475 buy you in modern China? Not a Tiffany diamond or a mini-sedan, say Robert Zhou and Daisy Chao. But for that price, they guarantee you something more lasting, with unquestioned future benefits: a U.S. passport and citizenship for your new baby. Zhou and Chao, a husband and wife from Taiwan who now live in Shanghai, run one of China's oldest and most successful consultancies helping well-heeled expectant Chinese mothers travel to the United States to give birth. The couple's service, outlined in a PowerPoint presentation, includes connecting the expectant mothers with one of three Chinese-owned...