More people born between 1980 and 1989 are remaining single compared to those who are 10 years older when they were at the same age, a survey released on Tuesday showed.

Nearly one in five men and one in eight women in the age group have never married, according to the survey conducted by the Center for Population and Development Policy Studies at Fudan University and the university's Research Center for Dataology and Data Science. The survey followed 1,200 Shanghai residents born during those years and their families for the past eight years.

In 2005, the ratio of men and women between 30 and 34 who remained unmarried was 12 percent and 7 percent, respectively, according to official figures.

"We cannot make a conclusion currently whether some in the age group, especially those born between 1985 and 1989, are just postponing marriage or have given up on marriage. We'll try to find the answer through the follow-ups," said Shen Ke, associate professor from the School of Social Development and Public Policy of Fudan University and one of the research leaders.

The survey also found 40 percent of those responding cohabitated before marriage, which used to be taboo in China, a country where people hold traditionally conservative attitudes toward sex.

Cohabitation contributes to the fact that people are getting married late, according to the survey report.

"For many, cohabitation is not a substitute for marriage but is a taste of married life to see whether they enjoy it or not. Roughly 60 percent of the survey respondents cohabit for no more than half a year, and then some break up," Shen said.