Pregnancy and childbirth during adolescence profoundly affects the lives of millions of girls worldwide, and is a leading cause of maternal mortality and morbidity, and infant and child mortality. Every year, an estimated 21 million girls aged 15–19 years old in low- and middle-income countries become pregnant, and approximately 12 million give birth. For many adolescent girls, the ability to control their sexual lives remains limited. Long-standing gender inequalities and discrimination, marginalization, harmful social and gender norms, and denial of rights, compounded by poverty and violence, render them vulnerable to early pregnancy, HIV and other health threats. Lack of age-appropriate sexual and reproductive health and rights (SRHR) information and services create additional barriers to care and support; as a result, adolescent girls who become pregnant are much more likely to go on to have rapid repeated births.