Teen fertility in transition: recent and historic trends in the United States.

After considerable declines in teen birth and pregnancy rates between 1991 and 2005, teen birth rates rose unexpectedly in 2006 and 2007. To understand these recent trends, we examined historical changes in fertility, trends in sexual behaviors, social forces, and public policies that may influence teen fertility. Although social forces such as poverty are critical in shaping adolescent reproductive choices, these do not explain rapid change in teen pregnancy risk since 1991. These recent changes, including increases in teen births since 2005, follow closely changes in teen contraceptive use. Likewise, contraceptive use is critical in explaining differences between U.S. and European fertility patterns. Public policies related to HIV prevention and sexuality education may have played a critical role in influencing teen pregnancy risk.