Updated

Carrie Bradshaw of "Sex and the City" once famously questioned whether bisexuality actually exists or whether it's just a "layover on the way to gaytown."

Turns out it's the real deal.

A new study finds that bisexuality in women appears to be a distinctive sexual orientation and not an experimental or transitional stage that some women adopt "on their way" to lesbianism.

The research, published by the American Psychological Association in the January issue of Developmental Psychology, followed 79 non-heterosexual women over 10 years and found that bisexual women maintained a stable pattern of attraction to both sexes.

Click here for the full study.

"This research provides the first empirical examination of competing assumptions about the nature of bisexuality, both as a sexual identity label and as a pattern of nonexclusive sexual attraction and behavior," wrote University of Utah psychologist Lisa Diamond, who conducted the study.

"The findings demonstrate considerable fluidity in bisexual, unlabeled and lesbian women’s attractions, behaviors and identities and contribute to researchers’ understanding of the complexity of sexual-minority development over the life span."

Diamond used interviewed data collected from the study participants five times over a 10-year period. The subjects, who identified as lesbian, bisexual or unlabeled, were 18 to 25 years old at the beginning of the study.

The findings included:

— Bisexual and unlabeled women were more likely than lesbians to change their identity over the course of the study, but they tended to switch between bisexual and unlabeled rather than to settle on lesbian or heterosexual as their identities.

— Of the respondents, 17 percent switched from a bisexual or unlabeled identity to heterosexual during the study — but more than half of these women switched back to bisexual or unlabeled by the end.

— By year 10, most of the women were involved in long-term (more than a year in length) monogamous relationships — 70 percent of the self-identified lesbians, 89 percent of the bisexuals, 85 percent of the unlabeled women and 67 percent of those who were then calling themselves heterosexual, dispelling the myth that bisexuals are reluctant to settle down.

— Women’s definitions of lesbianism appeared to permit more flexibility in behavior than their definitions of heterosexuality. For example, of the women who identified as lesbian in the last round of interviews, 15 percent reported having sexual contact with a man during the prior two years. In contrast, none of the women who settled on a heterosexual label at that point reported having sexual contact with a woman within the previous two years.

Diamond wrote: "This provides further support for the notion that female sexuality is relatively fluid and that the distinction between lesbian and bisexual women is not a rigid one."