In December 2025, the Food and Drug Administration approved a label change for Pfizer's birth control shot Depo-Provera, specifically adding a warning regarding the potential risk of developing meningioma, a type of brain tumor. This decision comes as Pfizer faces a lawsuit from over 1,000 women who allege that the company failed to warn about this risk despite historical studies suggesting links between progesterone and meningioma dating back to 1983. The lawsuit claims that Pfizer neglected its duty to investigate these risks sooner. While the overall incidence of meningioma is low, with around 39,000 cases diagnosed annually in the U.S., the concern is particularly significant for higher-risk demographics, including Black women who use the drug at nearly double the national rate. Pfizer had first acknowledged the risk in 2023 and then sought FDA approval for a label change in February 2024, which was initially denied due to the FDA's position on the evidence from observational studies. However, pressure continued to mount. Only after Pfizer amended and resubmitted its application did the FDA ultimately approve the warning in December 2025, highlighting the used progestin injections — Depo-Provera CI and Depo-Subq Provera 104. The label change was also part of a larger global trend, as countries like Canada and South Africa had already added similar warnings to their labels earlier. Pfizer has stated its commitment to the safety and effectiveness of Depo-Provera, while the attorneys representing the lawsuit’s plaintiffs argue that Pfizer has long misled patients and healthcare providers about the association between the drug and meningiomas. The FDA's decision aims to inform and protect women who might be affected, which the lawyers assert is a necessary step after years of confusion and risk exposure.

The history of progesterone and meningioma studies is a notable topic that explores the intricate relationship between hormonal influences and the development of certain types of brain tumors. Meningiomas, which are typically benign tumors arising from the meninges, have garnered attention in the scientific community due to varying incidence rates and potential hormonal associations. Progesterone, a steroid hormone, has been suggested to play a role in the growth and development of these tumors, leading to various studies that investigate this connection further. The historical context of this relationship dates back to earlier observations where fluctuations in female sex hormones, particularly during pregnancy, were noted to affect tumor size and growth, suggesting a potential link between these hormones and meningiomas. In the early studies, researchers aimed to determine whether there was a significant correlation between progesterone levels and the incidence of meningiomas. Initial findings were somewhat inconsistent, prompting further investigation into the mechanisms by which progesterone might influence tumor development. Some studies indicated that progesterone receptors were present in meningiomas, thus setting the foundation for the hypothesis that progesterone could stimulate tumor growth. Moreover, hormonal replacement therapy, commonly used in postmenopausal women, has also been explored for its potential impacts on meningioma risk, revealing an enhanced understanding of how exogenous hormone levels might contribute to tumor pathology. As research advanced, the attention on progesterone grew alongside innovations in molecular biology and genomics, allowing for more sophisticated analyses of tumor samples. Subsequent studies utilized advanced imaging techniques and histopathological examinations to ascertain the expression of progesterone receptors in meningioma tissues. The affirmation of progesterone receptor presence in many meningiomas has led to improved comprehension of the hormonal regulation of these tumors, although the exact role of progesterone in tumor progression remains an area of active investigation. Factors like tumor grade, location, and patient demographics have also been shown to modulate this relationship, underscoring the complexity of cancer biology. Recent meta-analyses have consolidated existing data, emphasizing the necessity for caution in interpreting the role of progesterone in meningioma development and growth. While a definitive causal link has yet to be established, the historical trend in research highlights the evolving understanding of hormonal impacts on brain tumors. Future studies are expected to further unravel the hormonal influence, focusing on targeted therapies that might disrupt the hormonal environment of meningiomas. The continued exploration of progesterone in this context holds promise for better diagnostic, prognostic, and therapeutic strategies for managing meningiomas.