In a culture where women marry young and marry up, those who also want success for themselves frequently find that the deck is stacked against them

Wei Pan on lunch break at her pharmaceutical research company / Sushma Subramanian.

SHANGHAI, China -- Wei Pan, a 33-year-old biomedical engineer can't seem to find Mr. Right. A fresh-faced woman with an M.D. and Ph.D. under her belt, Wei should have her pick of men. She has tried everything: online dating, set ups, social clubs like Toastmasters. She even took her search to the outdoor marriage market at Shanghai's People's Park, where, every weekend, parents of the unwed blanket the park with their children's resumes. Wei, who went with her mother, was disappointed that few singles actually showed up.

But it gave her a chance to scope out her competition. The resumes fluttering from taut clotheslines relayed the hard facts: age, height, education, property, salary. As she read through them, Wei realized that many of Shanghai's single ladies are just like her: highly educated, career-driven, and not getting any younger.

The Chinese media has been buzzing with stories about urban single women like Wei, so-called sheng nu, which literally translates to "leftover women." In a country where the sex ratio at birth has increasingly skewed toward men since the 1980s, the numbers may seem to favor women; but there's another force working against this class of ladies.* The country's long-held tradition of marriage hypergamy, a practice in which women marry up in terms of income, education and age, means that the most highly-educated women often end up without partners. Under these conditions, "men at the bottom of society get left out of the marriage market, and that same pattern is coming to emerge for women at the top of society," says Yong Cai, a University of North Carolina demographer who studies China's gender imbalance.