Last weekend, I was a groomsman at a friend's wedding, a British man marrying a Shanghainese girl. I say girl, but she was 33 years old. She had left it late; an unmarried woman over 30 in Shanghai is roundly considered a sheng nu - a leftover woman. Yet, looking at the five bridesmaids, all contemporaries of the bride, it occurred to me that four of them were still single. These women are part of a growing trend. According to the latest population census, between 2000 and 2010, the number of single women between 30 and 44 increased by 2.7 per cent. Shanghai is getting richer and its citizens better educated; better educated people get married later, right? Perhaps, but that doesn't tell the whole story; over the same period the number of single men between the ages of 30 and 44 decreased by 1.4 per cent. Shanghai may be following in Hong Kong's footsteps; figures from the Census and Statistics Department reveal that in 2009, 985,500 of the city's 7 million people were women who had never married, compared with 753,600 in 1996 - a rise of more than 30 per cent in 13 years. In the same period, the number of single men grew much less dramatically, just 17 per cent, from 847,100 to 988,700. So why are there all these single women in a society that pressures them to pair off young? The bridesmaids at the wedding were all attractive, intelligent and successful girls. One of them was a genuine looker who works for Morgan Stanley - it's safe to say she earns more in a year than I do in a decade. But therein may lie the rub. Shanghai's economy may be developing at a breakneck pace but age-old ideas about gender roles may be harder to alter, held back by an insidious little beast known as male pride. Last year, 46 per cent of unmarried people in Shanghai held college diplomas or above, up 23 per cent from 2000. Meanwhile, cross-regional marriage has seen a sharp rise, according to the city's marriage management division. Could it be that these men would rather enter a marriage in which they were sure to be wearing the trousers than one with a successful Shanghai girl equipped to boss them about? 'As far as I'm concerned, not many men want to accept a woman having a higher diploma than themselves,' says Mao Tian, one anxious Shanghainese father. 'My daughter has a master's degree, and I think she has a relatively narrower choice range than other women.'