In 2008, rates of teen pregnancies in the US reached their lowest level in nearly 40 yearsSince their peak in the early 1990s, they have fallen dramatically, as have rates of resulting births and abortions, according to a new report released this week from the Guttmacher Institute, a not-for-profit sexual health research group whose analysis finds that rates are down among all racial and ethnic groups, although disparities remain.

The report shows that in the US: Teen pregnancy rate in 2008 was 67...