It's not from increased use of birth control, as teenage contraceptive use has remained constant over the last twenty years. Nor is sex education to thank, as both states with comprehensive programs and states with none at all have witnessed relatively equal drops in teen pregnancy. Rather, there has been a shift from condom use alone to more effective methods, like the pill and IUDs. Health authorities have advised more girls to choose these options, recognizing that half of teens that use condoms do not do so consistently. Teen pregnancy has fallen by 44%; abortions have fallen by one-half.