Can IVF Cause Breast Cancer?
If you’re trying to get pregnant, in vitro fertilization (IVF) may be the best or only option you have. But could IVF increase your risk of breast cancer?
It’s true that when you go through IVF, the amount of estrogen and progesterone in your body goes up. And some breast cancer cells use these hormones to grow and multiply.
But most large studies suggest that being exposed to higher estrogen levels during IVF doesn’t increase breast cancer risk.
IVF leads to higher estrogen levels
IVF involves many steps. In general, a clinician takes eggs from a person’s body, combines the eggs with sperm to form embryos, and then transfers healthy embryos back into the body. For the best chance at success while undergoing IVF, people take hormone medicines. Some of these may include:
birth control to control the menstrual cycle
follicle-stimulating hormone (FSH) and human chorionic gonadotropin (hCG) to stimulate the ovaries to make multiple eggs
estrogen to brace the ovary to release eggs
progesterone to prepare the lining of the uterus to support an embryo
If you have breast cancer, your fertility specialist may have you take an aromatase inhibitor during IVF to reduce your estrogen levels.
Estrogen and breast cancer
About 75% of breast cancers are estrogen receptor- and/or progesterone receptor-positive. Breast cancers that have estrogen and progesterone receptors use these hormones to grow.
Studies have found that prolonged estrogen exposure can increase risk of hormone receptor-positive breast cancer. But these studies often looked at women who took hormones for several years, not a few weeks or months, as a person might when going through IVF.
What the research shows
Dozens of studies have looked for links between IVF and breast cancer.
One analysis combined data from 25 studies that looked at the relationship between fertility treatments and breast cancer. After studying data from over 600,000 women, the researchers found no increased incidence of breast cancer in women treated with hormonal fertility treatment for up to 10 years. Another study from the Netherlands compared outcomes in 25,000 women. After a follow-up period of 20 years, the researchers found breast cancer risk was about the same in women who did and didn’t receive IVF.
Researchers have also looked at IVF in people known to be at high risk for breast cancer. In one study, researchers found that IVF did not increase the risk of breast cancer for people who have a BRCA1 or BRCA2 mutation.
Studies of people with a history of breast cancer have similar findings. One study focused on women who had been diagnosed with breast cancer before the age of 44, and treated, who later gave birth. Some of the women got pregnant using IVF, while the rest got pregnant naturally. The researchers followed up with the groups for about 10 years. Compared with the women who got pregnant naturally, those who received IVF were no more likely to have breast cancer come back (recurrence).
Additionally, early results from the POSITIVE trial found that younger women diagnosed with early-stage, hormone receptor-positive breast cancer could safely pause hormonal therapy to try to become pregnant. In total, 36% of these women used assistive reproductive techniques, including IVF.
“Overall, the data appear to say that IVF is safe and does not increase the risk of breast cancer,” says Terri Woodard, MD, a reproductive endocrinologist at MD Anderson Cancer Center. Still, she thinks more long-term studies of people who received IVF are needed.
Infertility and breast cancer
While fertility drugs don’t seem to increase the risk of breast cancer, research suggests that infertility might increase breast cancer risk.
There are many causes of infertility or subfertility (which means it’s difficult for someone or a couple to conceive but not impossible), says Britton Trabert, MS, MSPH, PhD, a cancer epidemiologist at the Huntsman Cancer Institute at the University of Utah. Also, people with fertility issues may have children later in life and higher breast density, which can increase their risk of breast cancer.
Questions to ask
If you’re being treated for breast cancer or are at high risk of breast cancer recurrence, it makes sense to talk with your doctors about how to approach your situation. Here are a few questions that you might want to ask your oncologist:
Is pregnancy safe for me? What about fertility drugs?
Should I get a mammogram before IVF?
Are there any medicines you recommend I take during IVF to reduce my risk of breast cancer?
Here are questions to ask a fertility specialist:
Will IVF significantly delay my treatment?
Is ovarian stimulation — with in vitro fertilization — the only realistic option for getting enough eggs?
What are the potential complications of ovarian stimulation? Is there another type of fertility treatment that is less complicated?
What are the medical, financial, and scheduling demands and costs involved with IVF?
This content is made possible, in part, by Novartis, Lilly, and Pfizer.
— Last updated on September 29, 2025 at 5:40 PM