The most common reason women stop taking the pill is because they believe they are experiencing side effects such as feeling low or wanting to have sex less often.
But researchers at Umeå's University Hospital believe these side effects are frequently imagined by patients and are based on preconceptions of how previous kinds of contraceptive pills affected women, in contrast to the latest drugs on offer.
Marie Bixo, Professor of Obstetrics and Gynecology is leading a study involving 300 women from Uppsala, Stockholm, Örebro, Linköping and Umeå, which will run for two years.
During the trial, some women will be given sugar pills while others will be given birth control pills.
"Perceived side effects make women stop, sometimes abruptly leading to unplanned pregnancies or them choosing less secure methods. We believe that these mood side effects are not as common as you might think," Bixo told Swedish news network SVT.
"Many women feel bad at some point in life. It's very easy to blame it on hormones. Women talk a lot about not tolerating hormones or feeling bad because of hormones," she added.
Students at Umeå University who spoke to The Local remained unconvinced by her theory.
"I suddenly became constantly low," said 22-year-old Liss Jonasson about her first experience of the pill aged 17.
She said she had since tried a variety of different oral contraceptives and that all had affected her sex drive.
"It was a huge problem when I had a boyfriend because I wanted to have sex, only my body didn't. I've decided to quit the pill again and see what happens," she added.
Anna Svedberg, also 22, said:
"I stopped with the pill, because I almost strangled someone when I dropped a fork. I was in a constant state of PMS".
But she added that she had since switched to a different brand.
"Hormones scare me but taking the pill is easy and feels less invasive than other methods like the coil".
Sweden has a reputation for being more sexually permissive than many other nations.
Sweden has a low rate of teenage pregnancies with only 0.7 percent of girls aged 15 to 19 giving birth each year. By contrast, abortion rates are high
Abortion rates increased from 18.4 per 1,000 women in 1997, to 20.9 in 2012. Sales of the morning after pill have also soared in recent years.