There’s substantial reason to believe so. The potential link between synthetic progestins like medroxyprogesterone acetate (the active ingredient in Depo-Provera) and brain tumors has been discussed in medical literature since the early 1980s. Research dating back to 1983 highlighted that these hormones can activate receptors found in meningiomas—raising early concerns.

European regulators acted on this by requiring Pfizer to include a warning about meningioma risks. Canada followed suit. Yet, in the U.S., no such warning was added for years.

This omission raises serious questions. The scientific data was available, and global regulators took action. The fact that U.S. labeling remained unchanged suggests Pfizer prioritized continued sales over consumer safety.