Charlie Saunders writes: A study has recently been published in the New England Journal of Medicine (NEJM) which uses survival analysis to examine long-acting reversible contraception (e.g. intrauterine devices [IUDs]) vs. short-term commonly prescribed methods of contraception (e.g. oral contraceptive pills) on unintended pregnancies. The authors use a convenience sample of over 7,000 women. I [.