Researchers are developing an injection that creates a contraceptive implant in the body using an approach that could herald a new way of delivering drugs over long periods of time. Current contraceptive implants last for years, meaning women do not have to take a pill every day, but the devices must be fitted by a trained professional via a small surgical procedure. Now scientists say they have completed proof-of-concept experiments for a new type of long-lasting implant that self-assembles in the body.