For many, it is a convenient and effective form of contraception.
But, according to a new study, a form of the coil could be linked to anxiety and depression in nearly a fifth of the women who choose to have one each year.
The finding comes as growing numbers of women are opting to have the coil, a T-shaped device which is implanted in the womb. These use either copper (known as an intrauterine device, or IUD) or hormones (known as an intrauterine system, IUS) to prevent pregnancy.
Unlike the Pill, which women have to remember to take every day, the devices can be left in place for between three and ten years and only surgical sterilisation is better at preventing pregnancy.
The IUS is also often billed as being safer than the Pill because the hormones they release are contained within the womb; with a swallowed pill, they are dispersed throughout the whole body, including the brain.
Long-acting forms of contraception, heavily promoted by the NHS, have almost doubled in use in ten years, from 21 per cent in 2007 to 40 per cent in 2017.