Even though they’re more effective at preventing pregnancy than most other forms of contraception, long-acting birth-control methods such as intrauterine devices and hormonal implants have been a tough sell for women, especially younger ones. But changes in health-care laws and the introduction of the first new IUD in 12 years may make these methods more attractive. Increased interest in the devices could benefit younger women because of their high rates of unintended pregnancy, according to experts in women’s reproductive health.