One in four sexually active women has used injectable hormonal contraception at least once, which is administered intramuscularly in a doctor's office, most often every three months. However, many users are unaware of the potential increased risk of meningioma — the most common primary tumor of the central nervous system in adulthood. The topic has been back in focus in recent months due to new epidemiological analyses, regulatory updates to warnings in several countries, and fresh recommendations from professional societies. Given today's date (October 14, 2025), it is important to explain precisely what the new findings mean for women who use or are considering injectable contraception, as well as for those receiving other forms of progestin therapy.

What is a meningioma and why is it more common in women

A meningioma is a tumor that arises from the brain's protective membranes (meninges). In adults, it accounts for a significant proportion of primary brain tumors. In clinical practice, there are three grades according to the WHO classification: grade 1 (most common, slow-growing), grade 2 (atypical), and grade 3 (anaplastic, malignant). The proportion of low-grade tumors is estimated to be approximately two-thirds of all cases, while malignant meningiomas are rarer. The five-year survival for grade 1 is generally high, especially when the tumor is completely removed by neurosurgery, with the possibility of adjuvant radiotherapy if the tumor remains or if its location makes complete removal unfeasible. For grade 3, however, the risk of recurrence is higher, and the five-year survival is significantly lower compared to low-grade tumors, depending on the patient's age, location, and the treatment provided.

It is epidemiologically noticeable that meningioma is 2–4 times more common in women than in men. The scientific community has been debating the role of sex hormones in the biological behavior of meningiomas for decades. Clinical observations show that pregnancy can accelerate the growth of meningiomas, and regression is sometimes recorded after childbirth or cessation of hormone therapy. Such patterns support the hypothesis of hormonal sensitivity in at least a subset of meningiomas, particularly to progesterone receptor agonists.

MPA and why it is important in this story

Medroxyprogesterone acetate (MPA) is a synthetic progestin. In gynecological practice, it is used in various forms and doses: as an intramuscular injection for contraception administered by a healthcare professional (every 3 months), as a lower-dose subcutaneous injection that a woman can administer herself, in certain combinations for perimenopausal and postmenopausal hormone therapy, and, in some protocols, as part of gender-affirming care for transgender women. The key difference between various applications is often the dose and method of administration, which can alter the exposure of target tissues and potential risks.

What recent studies say about injectable contraception

Several large analyses in the last year and a half have sought to quantify the risk of meningioma in women using intramuscular MPA injections as a means of contraception. The results indicate an increased relative probability of a meningioma diagnosis compared to women who do not use this form of contraception. Two elements are particularly important for proper interpretation: duration of use and age at initiation. The most pronounced increase in relative risk was described with long-term use (e.g., four or more years) and in women who started the injections later in adulthood. However, the absolute risk at the population level remains low because meningioma is, after all, a rare diagnosis, and most users will never develop it.

Additional analyses also showed a difference among various contraceptive methods: in the data available so far, no increased risk was observed with levonorgestrel-releasing intrauterine systems (IUDs), while certain oral progestins and injectable MPA at higher doses and longer duration of use were associated with a higher risk. This heterogeneity among progestins can be explained by differences in chemical structure, dose, receptors, and pharmacokinetics.

Regulatory measures and differences among jurisdictions

In recent years, European and Canadian regulatory agencies have repeatedly updated the summaries of product characteristics and patient information materials, introducing more prominent warnings about the potential link between long-term use of certain progestins — including injectable MPA — and the risk of meningioma. In the United States, however, the warning labels still differ from European ones, which has sparked a debate about the consistency of regulatory approaches. In parallel, public and professional communication is increasingly focused on individualized patient information and shared decision-making about contraception, especially with longer cumulative exposure to injections.

What these numbers mean for real women

Relative risk tells us how much more likely an event is in one group compared to another, but it does not describe the probability in absolute numbers. Although recent analyses show that the risk of meningioma is higher in long-term users of injectable MPA, the absolute number of cases remains small. For example, even in the most unfavorable subcategories (long-term use, starting after age 31), a very large number of users is needed to statistically attribute one additional case of meningioma. This, of course, does not mean the risk is negligible — especially for women who have additional risk factors or symptoms compatible with a tumor — but it emphasizes the necessity of a nuanced conversation with a doctor instead of abruptly discontinuing therapy without professional advice.

Symptoms to watch out for

Meningiomas grow slowly and can be asymptomatic for years. When symptoms do appear, they depend on the tumor's location and may include headaches that change pattern or worsen, vision problems (double vision, loss of visual field), seizures, weakness or numbness in the limbs, speech difficulties, personality changes, and balance problems. In women with a longer history of injectable MPA use who develop new or progressive neurological symptoms, it is recommended to promptly contact a family doctor or a specialist directly to assess the need for neuroradiological imaging (brain MRI with and without contrast).

Diagnosis and treatment: from monitoring to radiotherapy

The standard for diagnosis is magnetic resonance imaging, which, with its characteristic findings (e.g., "dural tail"), often allows for a high level of suspicion for meningioma before surgery. Treatment is individualized: smaller, asymptomatic tumors may only be monitored with serial MRIs; surgical removal is the cornerstone for symptomatic or growing tumors when technically feasible; and radiotherapy — either as stereotactic radiation for smaller lesions or fractionated radiotherapy — is used alone or as an adjunct after surgery, depending on the grade, resection margin, and anatomical relationships.

We also spoke with oncologists who plan radiation for meningiomas, who emphasize that the benefits and risks of radiotherapy, alternatives like active surveillance and surgery, and possible side effects are discussed in detail with patients. For patients concurrently using progestin therapies, an important additional step is to assess whether hormonal exposure can be reduced or discontinued, especially if there is a suspicion that the tumor shows hormonal sensitivity. In many cases, stabilization or slowing of tumor growth has been observed after discontinuing the at-risk progestin, further suggesting a biological link.

What about other hormone therapies

Besides contraception, progestins are used in menopausal hormone therapy, for treating gynecological problems, and in gender-affirming care for transgender women. In these contexts, reports and cohort analyses have been published that suggest an increased risk of meningioma, especially with high doses and long-term use. However, the approach must be careful: in some patients, hormone therapy plays a key role in their quality of life or is medically indicated, so the benefit-risk assessment must be made together with a doctor, considering alternative regimens, doses, and types of progestins.

Why do tumors grow under the influence of progestins

Laboratory research aims to elucidate the molecular mechanisms. A large proportion of meningiomas express progesterone receptors, and a smaller proportion express estrogen receptors. Activation of the progesterone receptor can promote the proliferation of tumor cells and alter the expression of genes involved in angiogenesis and the cell cycle. Not all progestins are the same: they differ in their affinity for receptors, their effects on other steroid receptors, and their metabolic effects, so the risk may also differ between molecules. Furthermore, the pharmacokinetics of injectable MPA (high dose and prolonged action) further distinguishes this form of exposure from, for example, intrauterine systems with local progestin release.

How common is meningioma and how to "read" the numbers

In larger populations, tens of thousands of meningioma cases are diagnosed annually, but it is still a relatively rare disease given the total number of women using hormonal contraception. When ratios like "double" or "five-fold" risk increase are mentioned in the media, it is easy to lose perspective on the absolute values. In practice, for most users of injectable contraception, the lifetime probability of developing a meningioma remains low, but it increases with the duration of exposure and with age, as well as with other risk factors (e.g., previous head radiation, rare genetic syndromes).

What to do if you are already using injections

If you have a history of several years of injectable MPA use, especially if it started after the age of 31, it is rational to open a conversation with your gynecologist or family doctor. This does not mean automatically giving up contraception, but rather exchanging information about personal priorities (effectiveness, side effects, comorbidities), available alternatives, and your individual risk profile. Many women successfully switch to methods with no observed increase in meningioma risk, such as levonorgestrel-releasing intrauterine systems or non-hormonal options.

For women who decide to continue with injections, it is useful to regularly evaluate the therapy, monitor for new symptoms, and consider periodically reassessing the need for continuation after a few years, especially if life circumstances have changed (for example, completed reproductive phase, new chronic diseases, planned surgeries).

Specific groups: postmenopause and gender-affirming care

In postmenopausal hormone therapy, progestins are most often combined with estrogen in women with a uterus to reduce the risk of endometrial hyperplasia. If a woman has a diagnosed meningioma or a high risk for meningioma, a therapeutic adjustment may be considered (selecting a progestin with a more favorable safety profile, reducing the dose, shorter duration, stricter monitoring). Any deviation should be made in collaboration with subspecialists in gynecological endocrinology and neuro-oncology.

In gender-affirming care for transgender women, where progestins are sometimes used as part of hormone regimens, the indications, doses, and duration must be carefully considered. The emphasis is on informed consent and multidisciplinary management, with a clear plan for monitoring and communication about potential neurological symptoms.

The role of genetic and molecular tests

Molecular profiling of meningiomas (e.g., mutations in the NF2, AKT1, SMO, KLF4, TRAF7 genes) is increasingly becoming routine in reference centers. Such findings can inform prognosis, potential response to targeted approaches, or the intensity of monitoring. In the context of radiotherapy, integrating histopathological and molecular data helps to refine doses and radiation volumes and to plan follow-up examinations.

How to talk to your doctor: questions for your next check-up

• What is my individual risk considering the age, duration, and dose of the injectable contraception I have used?


• What alternative methods are equally effective for me and have no proven link to an increased risk of meningioma?


• Do I have symptoms that would suggest the need for a brain MRI or a neurological evaluation?


• If I already have a diagnosed meningioma, is there a benefit to stopping or changing my hormone therapy?


• How is monitoring planned, and at what time intervals?

Informed choice and digital resources

Women who want to learn more about contraceptive options can request verified informational materials from their doctor or visit the websites of relevant professional societies. It is useful to compare summaries of methods, understand the differences between systems that release hormones locally and those with systemic exposure, and check when the official safety documents were last updated.

What this means for the healthcare system

New findings also demand organizational responses: clearer and more consistent messages in drug information leaflets, integration of warnings into informed consent forms, educational programs for primary care physicians and gynecologists, harmonization between regulators in different jurisdictions, and available referral pathways for neuroradiological diagnostics when justified. The role of pharmacoepidemiological registries is key here as they allow for the rapid detection of safety signals in the real population.

Key messages for patients and doctors

• Injectable MPA contraception is associated with an increased relative risk of meningioma, especially with long-term use and initiation at a later age.


• The absolute risk remains low; most users will never develop a meningioma.


• The safety profiles of different progestins and methods vary — levonorgestrel-releasing intrauterine systems do not currently have a signal of increased risk.


• Discontinuing or changing the at-risk hormone therapy may lead to disease stabilization in some patients.


• Decisions should be made individually, in consultation with a doctor, without sudden moves and with respect for personal priorities.

Legal and social dimension

The debate over risk labeling and consumer information is also taking place in courts in some countries, where users claim they were not adequately warned of the potential risk after long-term use of injectable MPA. The outcomes of such proceedings could influence the future shaping of public health messages, physician education, and the format of informed consent. Regardless of the legal outcomes, the professional community emphasizes that communication about rare but potentially serious side effects must be clear, balanced, and free of sensationalism.

Alternative contraceptive options

For women who want to avoid systemic progestin exposure or reduce the cumulative dose, intrauterine systems, the non-hormonal (copper) IUD, progestin-only minipills with a different profile, implants, and barrier methods are considered. Each option has specific advantages and limitations (effectiveness, side effects, contraindications, convenience), so counseling is crucial to select the method that best suits one's health status and plans.

Research perspectives

Projects are underway to map in more detail which molecules, doses, and durations of exposure contribute most to the risk, with the integration of biological markers of tumor sensitivity to hormones. More data is also expected on the dynamics of risk after discontinuation of use — so far, observations suggest that the elevated risk decreases over time after stopping the injections, but precise time horizons are important for clinical decision-making.