There is no proven link between the hormone injections used in IVF and breast, ovarian or uterine cancer in women without pre-existing risk factors. The injections are a short course — usually 8 to 12 days — closely monitored by your doctor, and they don't stay in the body afterward. Fear of this shouldn't be a reason to delay fertility treatment.
Why this fear comes up
IVF uses hormone injections to stimulate the ovaries to grow more than one follicle in a cycle, instead of the single follicle a natural cycle produces. Because several cancers — breast, ovarian, uterine — are hormone-sensitive, it's a reasonable-sounding worry that raising hormone levels, even briefly, could raise cancer risk. It's also an old worry: IVF has been studied for decades specifically to answer this question.
What actually matters
- The course is short. A typical stimulation cycle runs 8 to 12 days of injections, not continuous or long-term hormone exposure
- It's closely monitored. Your doctor tracks your response through blood tests and follicular monitoring scans through the cycle, adjusting as needed
- The hormones don't stay in the body. Once the cycle ends, hormone levels return to your baseline — this isn't an ongoing exposure
- Pre-existing risk factors matter more than IVF itself. A family history of breast or ovarian cancer, or known BRCA gene changes, changes a person's cancer risk profile whether or not they ever do IVF — IVF itself isn't shown to add to that risk in women without those factors
- Infertility and delayed childbearing carry their own, separate associations with cancer risk that exist independently of fertility treatment — and these can get misread as "IVF caused this," when the underlying cause was the infertility or the delayed pregnancy itself, not the treatment
The short, monitored hormone course used in IVF has not been shown to raise cancer risk in women without pre-existing risk factors — fear of it is not a reason to delay treatment.
Frequently asked
Can IVF hormone injections cause breast cancer?
There is no proven link between the hormone injections used in IVF and breast cancer in women without pre-existing risk factors. A family history of breast cancer or a known BRCA gene change affects a person's individual risk regardless of whether they do IVF — tell your doctor about any family history before starting treatment so it can be factored into your care, not because IVF itself is shown to cause breast cancer.
Does ovarian stimulation raise the risk of ovarian cancer?
Large studies following women who underwent ovarian stimulation have not shown a proven causal link to ovarian cancer in women without existing risk factors. The hormone exposure during stimulation is short-term and monitored, unlike the sustained hormone exposure patterns that are more classically associated with ovarian cancer risk.
If infertility itself is linked to cancer risk, isn't that the same as saying IVF causes it?
No — these are different things. Some studies associate infertility and delayed childbearing with a slightly different cancer risk profile, independent of whether a person ever has fertility treatment. When a woman who was already infertile later develops cancer, it can look like "the IVF caused it," when the more accurate picture is that the underlying infertility or the delayed pregnancy carried that association on its own.
Should a family history of cancer stop me from doing IVF?
Not necessarily — but it's important information for your fertility specialist to have before you start. A family history of breast or ovarian cancer, or a known BRCA gene change, changes your individual risk profile and may change how your treatment is monitored. Discuss your full family history at your initial consultation so your doctor can plan your care around it.