January 28, 2025
By Eden Parks, Drexel University College of Medicine
The Depo-Provera shot is a very common form of birth control that contains the progestin medroxyprogesterone acetate. This hormone mimics progesterone, binding to the progesterone receptor and essentially functioning the same way as the hormone. As a form of birth control, there are several functions of this injection. It works to prevent ovulation, preventing the release of an egg from the ovary. It also thickens cervical mucus, inhibiting sperm from entering the uterine cavity. Additionally, it thins the uterine lining, making it less likely for an egg to implant in the uterine wall. The shot is administered to a muscle, typically the arm or buttock, every three months, and it is 96% effective.
A recent study was published suggesting a link between the Depo-Provera shot and the development of meningiomas. A meningioma is a tumor that grows from the meninges in the brain or spinal cord. They are the most common tumor of the brain and are most commonly benign. The study was conducted as a national case-control study using the French National Health Data System. The study analyzed several different forms of progestogens: progesterone, hydroxyprogesterone, dydrogesterone, medrogestone, medroxyprogesterone acetate, promegestone, dienogest and intrauterine levonorgestrel. The study found that prolonged use of medrogestone, medroxyprogesterone acetate and promegestone were found to increase the risk of intracranial meningioma. Of note, medroxyprogesterone acetate is the main progestin in the Depo-Provera shot. The study also noted that there was no increased risk with intrauterine levonorgestrel, the form of progestin in intrauterine devices. This study sparked concern that the Depo-Provera shot may be a danger to those using it, causing speculation regarding further use of this contraceptive.
This quickly became a controversial article, prompting response from the American College of Obstetrics and Gynecology, as well as replies to the editor. It was noted that the study has several limitations and warrants further research. The study, which included 18,000 patients affected by intracranial meningioma, had only 9 participants that had received intramuscular medroxyprogesterone. This is in contrast to hundreds who had received other forms of progesterone with no association in meningioma formation. To put the findings into perspective, it was noted that five out of 10,000 women using medroxyprogesterone acetate may possibly develop meningioma compared to one out of 10,000 women not using the medication.
The response article notes that it would be premature to draw conclusions from this data regarding associations between the injection and meningioma development. When calculating the number needed to harm, more than 2,300 individuals would need to use medroxyprogesterone for one associated case of meningioma to arise. The authors also note that the morbidity and mortality associated with an unplanned or mistimed pregnancy occurs at a significantly greater frequency than that of an intracranial meningioma. This underscores the importance of this contraceptive option and the need for further research on this matter before a definitive conclusion can be made.
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