About 16 million adolescent girls between 15 and 19 years of age give birth each year. Babies born to adolescent mothers account for roughly 11% of all births worldwide, with 95% occurring in developing countries. For some of these young women, pregnancy and childbirth are planned and wanted, but for many others they are not. There are several factors that contribute to unplanned and unwanted pregnancies in adolescence. Adolescents may be under pressure to marry and to bear children early, they may have limited educational and employment prospects. Some do not know how to avoid a pregnancy, while others are unable to obtain condoms and contraceptives to do so. Adolescents may be unable to refuse unwanted sex or to resist coerced sex. Those that do become pregnant are less likely than adults to be able to obtain legal and safe abortions to terminate their pregnancies. They are also less likely than adults to obtain skilled prenatal, childbirth and postnatal care.

Childbirth at an early age is associated with greater health risks for the mother. In low- and middle-income countries, complications of pregnancy and childbirth are the leading cause of death in young women aged 15–19 years. Unwanted pregnancies may end in abortions, which are often unsafe in this age group. There were an estimated 3 million unsafe abortions among 15–19 year olds in 2008.

The adverse effects of adolescent childbearing also extend to the health of their infants. Perinatal deaths are 50% higher among babies born to mothers under 20 years of age than among those born to mothers aged 20–29 years. Babies of adolescent mothers are also more likely to be of low birth weight, with the risk of associated long-term effects.

There is a growing recognition that adolescent pregnancy contributes to maternal mortality, to perinatal and infant mortality, and to the vicious cycle of ill-health and poverty. The Global Strategy for Women's and Children's Health, launched by the UN Secretary General in September 2010, stresses the importance of addressing the health and welfare of adolescent girls, especially towards achieving MDG-5 related to maternal mortality reduction.

The WHO Guidelines on preventing early pregnancy and poor reproductive outcomes among adolescents in developing countries provides recommendations on action and research for: a) preventing early pregnancy: by preventing marriage before 18 years of age; by increasing knowledge and understanding of the importance of pregnancy prevention; by increasing the use of contraception; and by preventing coerced sex; b) preventing poor reproductive outcomes: by reducing unsafe abortions; and by increasing the use of skilled antenatal, childbirth and postnatal care.

These guidelines are primarily intended for policy-makers, planners and programme managers from governments, nongovernmental organizations and development agencies. They are also likely to be of interest to public health researchers and practitioners, professional associations and civil society organizations.

They have been developed through systematic review of the evidence and technical expertise of policy-makers, programme managers and front-line workers from countries around the world, in partnership with many key international organizations working in this field. Similar partnerships have been forged to distribute them widely and to support their use.

In July 2010, the United Nations General Assembly held a high-level meeting on youth. At this meeting heads of state and governments, ministers and other governmental representatives committed to ensuring that the needs and problems of young people are recognized and addressed. Twenty-five United Nations bodies, including the World Health Organization (WHO), endorsed a joint commitment to intensifying efforts to develop comprehensive policies, multisectoral programmes, strengthened capacities and effective youth participation for youth development. These guidelines are an expression of WHO's commitment to the health and well-being of the world's adolescents and young people.

• Dr Elizabeth Mason
  Director
  Department of Maternal, Newborn, Child and Adolescent Health
  World Health Organization