If you took oral contraceptives as a teenager, you may be at higher risk of depression as an adult, even if you stopped taking the pill years ago, according to a new study from University of British Columbia researchers.

In a survey of over 1,200 adult women, researchers found that women who had used birth control pills in their teenage years were up to three times more likely to be clinically depressed than women who had never used the pill.

Teenage users were also 1.7 times more likely to become depressed later in life than women who only started using the pill as adults.

Christine Anderl, postdoctoral fellow at UBC's psychology department and the study's lead author, says the results show there's still much to learn about the long-term effects of hormonal birth control use.

"I really think that it's very important that women have safe and efficient birth control access, which is a universal right," said Anderl. "The one problem I see is that we still don't know all the side effects potentially and which women might be particularly at risk to experience the serious ones."

She notes women are twice as likely as men to develop depression at some point in their lives.

Anderl says animal studies have shown changes to sex hormones during puberty can have an irreversible impact on brain development, but the link between hormonal birth control use and depression for humans is less clear.

According to the study, published Wednesday in the Journal of Child Psychology and Psychiatry, the correlation between birth control use and depression was consistent even after the researchers controlled for other factors like age of first sexual intercourse, age of first period, socio-economic status, smoking history and previous pregnancies.

However, the data they used didn't show if there was an increased risk for women who had used oral contraceptives for a longer period of time.

Nicole Pasquino, the clinical director at Options for Sexual Health in Vancouver, says the findings aren't a reason for women or girls to stop taking birth control.

"Women who are on contraception have access to better family planning, complete education, they have autonomy, they have more power in the household, they have an increase in earnings, and all of these things have been shown to contribute to better mental health outcomes."

Pasquino says it's important for women and girls to have a conversation with their health care provider about their concerns to determine which method of birth control is best suited for them individually.

She also notes the survey didn't gather information about women's history of sexual assault or violence, which could also impact their mental health outcomes.

Anderl says more research is needed to determine whether using birth control pills as a teenager actually causes depression. Past findings have been conflicting, with some studies finding no relationship between hormonal contraceptive use and depression, and others establishing a correlation between a lower risk of depression and taking the pill as an adult.

Anderl's team is currently recruiting girls between 13 and 15 years old for a study that would measure their hormone levels and assess their emotional well-being over three years.

"The relationship seems to be there but at some point it would be really important to be able to say, does one really cause the other or is there a different factor?"

Anderl says establishing that direct link could change the way doctors talk about birth control with their patients, especially if they have a family history of depression.