The research, which was published in the British Medical Journal, found that prolonged use (12+ months) of the following three progestogens was associated with as much as a 5.6 fold increased risk of meningioma: medrogestone, promegestone and medroxyprogesterone acetate. These hormones are prescribed not only in the contraceptive medicine but also in two other medications for menopause relief and to treat several gynaecological conditions such as endometriosis and polycystic ovary. Both medrogestone and promegestone are used in menopausal hormone therapy and have been linked to an increased risk of intracranial meningiomas.

Meningioma are tumours that grow in the tissues surrounding the brain and spinal cord. While most meningioma are non-cancerous, many are, as they still account for 40 percent of cancers in the central nervous system. Additionally, these small tumours can have huge health implications, including loss of vision, hearing, smell and memory as well as causing seizures and weakness in the arms or legs. Meningioma can also put pressure on the brain which may lead to a need for surgical removal, a procedure which carries its own risks (one being brain damage).

However, some experts have argued the increased risk is relatively small and not to be feared. Cancer epidemiologist Professor Paul Pharoah stated: "This small increase in risk needs to be considered in relation to the benefits of using an injectable form of contraception”, despite there being several contraceptive drugs on the market that do not carry this risk.

Pfizer, the manufacturer of Depo-Porvera, issued the following statement: “We are aware of this potential risk associated with long-term use of progestogens and, in collaboration with regulatory agencies, are in the process of updating product

labels and patient information leaflets with appropriate wording.”

NHS data suggests there are around 10,000 prescriptions for the contraceptive medication every month in England and the hormones are taken in some form by millions of women around the world.

‍