Researchers from Altoona Hospital in Pennsylvania examined the results of 34 studies from around the world of young women who took oral contraceptives prior to becoming pregnant with their first child.
The researchers, led by Dr. Chris Kahlenborn, found that those young women experienced a 44 percent increased risk of developing pre-menopausal breast cancer, while women who took the pill for four years or longer prior to their first pregnancy ran an increased risk of 52 percent.
Kahlenborn's study -- published in the October issue of the journal Mayo Clinic Proceedings -- warns that most young women taking oral contraceptives seem to be unaware of the risks.
"As I studied the medical literature, I noticed that a trend appeared," said Kahlenborn. "Namely, OC (oral contraceptive) use prior to first-term pregnancy seemed to consistently increase the risk of pre-menopausal breast cancer.
"Although the trend was apparent, pre-menopausal women have continued to hear that OCs are basically safe."
Dr. Andrew Penman, CEO of Cancer Council NSW (New South Wales), said that although he believed the risk of breast cancer in women younger than 50 was minimal, most women in Australia were unaware of the possible risks of taking the pill.
"The problem with the pill is that it is such a money spinner that the money gets in the way of the risks," Penman said.
Penman recommended that governments invest in a "decision aid" to help young women make better-informed contraceptive decisions.