Throughout the world, the age of puberty is falling while the age of marriage is generally rising. These factors result in a longer period during which unmarried youth can be sexually active, often in a series of monogamous relationships.
For behavioral as well as physiological reasons, early sexual debut increases adolescents' risk for infection with HIV and other STIs. Youth who begin sexual activity early are more likely to have high-risk or multiple partners and are less likely to use condoms.
Many factors affect the timing of sexual debut. A World Health Organization review of studies in 53 countries found common protective factors and risk factors throughout the world. Having positive relationships with parents and teachers, holding spiritual beliefs, and attending school were associated with a decreased likelihood of early sexual debut. In contrast, engaging in other hazardous behaviors and having sexually active friends were associated with an increased likelihood of early sexual debut.
Delaying first sex or abstaining from sexual intercourse after having been sexually active may be difficult. Youth may not practice abstinence perfectly, just as they might not use condoms consistently and correctly. Some may consider themselves to be practicing abstinence if they abstain from vaginal intercourse, even if they engage in other kinds of sexual intimacy. A young person may have sexual intercourse in a "weak" moment, which emphasizes the need to help youth develop abstinence skills. Other youth may be coerced into sexual intercourse. However, delaying sexual debut or abstaining from sexual intercourse after having been sexually active can be empowering.