Around the globe, more than 1 billion young people, ages 15 to 24, are making the often-difficult transition to adulthood. They are changing physically, maturing emotionally, connecting socially and having sex with each other. But the consequences aren't as simple as they may once have been. The global economy is changing, and in most countries, young people need higher education to keep pace economically. As a result, the age of marriage is drifting upward. More adolescents are finding themselves exploring their sexuality outside of marriage, resulting in more out-of-wedlock pregnancies and births.
The public health toll is staggering: One in every 10 births worldwide is to a teen mom; at least one in 10 abortions worldwide is performed on young women ages 15 to 19. And every day, 500,000 young people are infected with a sexually transmitted infection (STI). A March 2008 study reported that one in four girls and young women, ages 14 to 19, in the U.S. has at least one of four common STIs—and nearly half of African-American females in the study have one of the STIs. Worldwide, more than 10 million people, ages 15 to 24, are infected with the HIV virus, many of them in Africa, according to UNICEF.
"In some ways, we are fighting biology," says Robert Wm. Blum, MD, PhD, MPH, the William H. Gates Sr. Professor and Chair of Population, Family and Reproductive Health (PFRH). "The social norms are changing. Historically, marriage and puberty would coincide. But as the age of marriage goes up, there's a greater period between fertility and marriage. So we are seeing this clash around the globe ... and a lot of countries are wrestling with it."
At the Bloomberg School, researchers are making strides toward understanding adolescent sexual behavior—and using that newfound knowledge to design programs aimed at helping teens make healthier decisions about their sexual lives.
Across countries, across cultures, a pattern is emerging, as researchers work to tease out "protective measures" that help teens avoid risky behaviors, such as drinking, taking drugs and having unprotected sex. The three leading factors to emerge: a connection to a caring adult, an interest in school and a stable community.
"We are starting to see a whole set of risk and protective factors in a kid's life," Blum says. "If some of these protective factors are in place, kids do better. ... They contracept, they delay first sex, and they are less likely to get into a whole slew of other problems as well."
Understanding Teens
Freya Sonenstein, PhD, director of the Bloomberg School's Center for Adolescent Health, has been working in this field since the late 1970s. Her groundbreaking work, the National Survey of Adolescent Males, was the nation's first comprehensive look at adolescent male sexuality (see sidebar). This year, surveyors begin a fourth round of interviews with the first boys, surveyed initially in 1988, now in their mid-30s. Based on the data, Sonenstein has seen a change in positive male behavior. "There's been a decrease in the level of sexual experience and an increase in age of first intercourse," says Sonenstein. "Boys have been delaying first sex and the percentage using condoms all the time has gone up."
Researchers Michelle Hindin, PhD '98, MHS '90, and Ushma Upadhyay, PhD '06, have turned their attention overseas. Hindin, a PFRH associate professor, is looking at the specific behaviors, within a specific culture, that lead to first sexual experiences. Since 2001, Hindin has worked with data from over 2,000 mothers and their children in Cebu, Philippines. Nearly all are Catholic. By age 18, 31 percent of boys and 20 percent of girls reported having premarital sex—low percentages compared to other nations.
Hindin's data show: Boys who progress to physical relationships earlier (holding hands, kissing) have sex earlier, whereas girls who progress to emotional attachments earlier (dating and emotional relationships) have sex earlier than female counterparts who don't have the same emotional relationships. Also, if mothers report equitable decision-making styles at home, sons report delaying first sex. If mothers report that they have high-status houses, daughters report holding off on first sex.
Another Bloomberg School researcher, Kathleen M. Roche, PhD '98, MSW, has spent a decade looking at U.S. parenting styles and how they affect adolescent behaviors, including early sex. Much of her work has focused on families living in low-income urban neighborhoods. Over the course of several peer-reviewed papers, she has pieced together recurring themes. First, there's some indication that uninvolved, ineffective parenting carries steeper penalties for young people in more dangerous neighborhoods. Second, there is considerable variability even within low-income neighborhoods. "There's a growing body of evidence to suggest that the stakes are even greater when families are faced with more risks," says Roche, a PFRH assistant professor.
And teens who fare best are those who perceive that the parent, or other concerned adult, genuinely cares about them and wants to provide them with a better future.
