Oral contraceptives do not increase the risk of ovarian cancer. They do the opposite: women who have ever used oral contraceptives have a 30% to 50% lower risk of ovarian cancer compared to women who have never used them. This protective effect is one of the most consistent findings in cancer epidemiology, confirmed across decades of research and multiple large studies.
How Much Protection the Pill Provides
The risk reduction is significant and dose-dependent, meaning the longer you take oral contraceptives, the greater the protection. The Oxford Family Planning Association study, which followed women for decades, found that ever-users had roughly half the ovarian cancer risk of never-users. That same study found protection was still detectable 28 or more years after women stopped taking the pill.
A large international analysis put more specific numbers on how the protection fades over time after stopping. Women who were currently on the pill or had stopped within the last 10 years had a 29% reduction in risk. For those who stopped 10 to 19 years earlier, the reduction was 19%. Even 20 to 29 years after quitting, risk was still 15% lower than in women who never used oral contraceptives. So while the benefit does weaken gradually, it persists for decades.
Why the Pill Lowers Risk
Two biological mechanisms explain the protective effect. The first is ovulation suppression. Each time an ovary releases an egg, the surface of the ovary ruptures and repairs itself. Over a lifetime, hundreds of these micro-injuries accumulate, and the repeated cell division during repair creates opportunities for DNA errors that can eventually lead to cancer. Oral contraceptives stop ovulation, dramatically reducing this cumulative damage.
The second mechanism involves hormones called gonadotropins, which stimulate the ovaries. The pill suppresses these hormones, reducing the amount of stimulation ovarian tissue receives. Less stimulation means less cell growth and, in theory, fewer chances for abnormal cells to develop.
Protection for Women With BRCA Mutations
Women who carry BRCA1 or BRCA2 gene mutations face a much higher baseline risk of ovarian cancer, making this question especially important for them. The evidence suggests oral contraceptives provide meaningful protection in this group as well, though the data is less precise than for the general population.
For BRCA1 carriers, the numbers are striking. Women who used oral contraceptives for 10 or more years had approximately a 63% reduction in ovarian cancer risk compared to those who used them for fewer than five years. Even 5 to 9 years of use was associated with roughly a 33% reduction. This protection also persisted long after stopping: BRCA1 carriers who had used the pill for 10-plus years still showed substantial risk reduction more than 15 years after their last use.
For BRCA2 carriers, the estimated reduction was comparable in size but did not reach statistical significance in available studies, likely because fewer BRCA2 carriers develop ovarian cancer, making it harder to detect the effect with certainty. The trend, however, pointed in the same protective direction.
The Broader Cancer Picture
Oral contraceptives don’t affect all cancers the same way. While they clearly reduce ovarian cancer risk and also lower the risk of uterine cancer by a similar magnitude (about 50%), they are associated with a modest increase in cervical cancer risk. Their relationship with breast cancer has been debated for years, with some studies showing a small, temporary increase in risk during current use that fades after stopping.
The Oxford Family Planning Association study, which tracked cancer outcomes over the longest period available, concluded that the beneficial effects of oral contraceptive use on cancer outweighed the adverse effects overall. The researchers specifically noted that their findings “should reassure older women who used OCs in the past.” For uterine and ovarian cancer combined, the protection increased with duration of use and was still measurable nearly three decades later.
What This Means in Practice
If you’ve taken the pill at any point in your life, you likely carry some degree of reduced ovarian cancer risk. The longer you used it, the stronger that protection. Five years of use provides meaningful benefit, and 10 or more years provides substantially more. This protective effect is not something you lose quickly after stopping; it stays with you for decades, gradually diminishing but never fully disappearing within the timeframes researchers have been able to study.
For women weighing contraceptive options, ovarian cancer protection is one factor among many. It’s particularly relevant for women with a family history of ovarian cancer or known BRCA mutations, where the baseline risk is high enough that a 50% or greater reduction carries real clinical weight. The pill was designed for contraception, but its effect on ovarian cancer risk is one of the most well-documented secondary benefits of any widely used medication.