New research suggests that millions of women using a common contraceptive pill may face a higher risk of developing a brain tumour. The mini-pill, a daily birth control tablet containing progesterone, is often prescribed as an alternative to the combined pill. However, scientists have found that women who take it for more than five years are more likely to develop a meningioma, a type of brain tumour. Although usually non-cancerous, these tumours can be dangerous as they grow and press on the brain, causing symptoms like headaches, seizures, and memory loss.

French researchers analyzed data from over 8,000 women who had surgery for meningiomas and found that many had been taking a mini-pill containing desogestrel, a type of progesterone, for five years or longer. The study revealed that the increased risk of developing a meningioma was only seen in those who had taken the mini-pill for five years or more, and it disappeared within a year of stopping treatment.

Health experts have advised women not to be alarmed, emphasizing that the overall risk remains very low. While the study found a link between long-term use of the mini-pill and meningioma, the researchers stressed that the increased risk was small. They estimated that only one in every 67,000 women taking desogestrel would develop a meningioma requiring surgery.

Meningiomas are tumours that form in the lining of the brain and can cause serious problems as they grow. Common symptoms include persistent headaches, nausea, and drowsiness. The study also highlighted a key limitation - it only focused on one type of mini-pill, desogestrel, and did not assess other progesterone formulations.

Experts have called for further studies to be conducted in other countries to assess the risk more widely. In the UK, around six percent of women aged 16 to 49 currently use the mini-pill, which is over 99 percent effective when used perfectly. However, with typical use, around one in ten women may become pregnant due to missed pills or illness.

Side effects of the mini-pill can include nausea, headaches, mood swings, and breast tenderness. While some users report weight gain, there is no evidence that the pill causes this. The latest research adds to previous findings that women with asthma who take the mini-pill may be at a higher risk of suffering an attack.