In September 2000, 189 world leaders signed a declaration on eight Millennium Development Goals (MDGs) to improve the lives of women, men, and children in their respective countries (United Nations General Assembly 2000). Goal 5a calls for the reduction of maternal mortality by 75 percent between 1990 and 2015. Goal 5a was supplemented by MDG 5b on universal access to contraception. MDGs 5a and 5b have been important catalysts for the reductions in maternal mortality levels that have been achieved in many settings. Despite substantial progress, challenges remain. The majority of low-income countries (LICs), particularly in Sub-Saharan Africa and postconflict settings, have not made sufficient progress to meet MDG 5a. The post-2015 agenda on sustainable development is broader than the MDG agenda, with a greater number of nonhealth goals and a strong focus on inequity reduction; the new agenda includes an absolute reduction in maternal mortality as a marker of progress. This new indicator is expected to be framed as targets for preventable maternal deaths (Bustreo and others 2013; Gilmore and Camhe Gebreyesus 2012). The International Classification of Diseases (ICD-10) defines maternal death as “[The] death of a woman while pregnant or within 42 days of the end of pregnancy, irrespective of the duration and site of the pregnancy, from any cause related to or aggravated by the pregnancy or its management, but not from accidental or incidental causes” (WHO 2010, 156). Subsequent guidance on the classification of causes includes nine groups of underlying causes (box 3.1) (WHO 2012). Despite the increased global focus on maternal mortality as a public health issue, little detailed knowledge is available on the levels of maternal mortality and morbidity and the causes of their occurrence. A large proportion of maternal deaths occur in settings in which vital registration is deficient and many sick women do not access services. To obtain data on population levels of maternal mortality in these settings, special surveys are needed, including the following (Abouzahr 1999): Reproductive Age Mortality Studies, which investigate all reproductive age deaths. Demographic and Health Surveys, which interview women and men about their siblings’ survival in adulthood to identify deaths of sisters during or following pregnancy (the siblings are from the same mother) (Ahmed and others 2014). Smaller studies, which use the indirect sisterhood method. National investigations, which add questions to censuses. Verbal autopsy studies, which provide information on causes and circumstances of deaths. Maternal death studies require large sample sizes; recent national-level data are often nonexistent, and maternal mortality tracking relies principally on mathematical models. This lack of data has led to a repeated call for countries to improve their vital registration systems and to strengthen other mechanisms for informing intervention strategies, such as the maternal death surveillance and response system proposed within the new accountability framework (WHO 2013). Accountability remains a central part of United Nations Secretary General Ban Ki-Moon’s updated global strategy to accelerate progress for women’s, children’s, and adolescent’s health (http://www.everywomaneverychild.org/global-strategy-2). The accountability framework, developed under the 2010 global strategy to accelerate women’s and children’s health, included recommendations for improvements in resource tracking; international and national oversight; and data monitoring, including maternal mortality (Commission on Information and Accountability for Women’s and Children’s Health 2011). Information on maternal morbidity is frequently collected in hospital studies, which are only representative of patients who seek care. Community-based studies are rare in LICs and suffer from methodological limitations, particularly when they rely on self-reporting of obstetric complications. Self-reporting is known not to agree sufficiently with medical diagnoses to estimate prevalence. In particular, studies validating retrospective interview surveys find that women without medical diagnoses of complications during labor frequently reported symptoms of morbidity during surveys, a phenomenon that can lead to an overestimation of prevalence (Ronsmans and others 1997; Souza and others 2008). In addition, community-based studies have focused on direct obstetric complications; little is known about the nature and incidence of many indirect complications that are aggravated by pregnancy. For example, reliable population-based estimates of the occurrence of asthma during pregnancy do not exist in LICs. This chapter addresses the extent and nature of maternal mortality and morbidity and serves as a backdrop to subsequent chapters on obstetric interventions in LICs. It introduces the determinants of maternal mortality and morbidity and their strategic implications. The next section uses the most recent estimates from the World Health Organization (WHO) to show that women face a higher risk of maternal death in Sub-Saharan Africa. It discusses the recent findings of a WHO meta-analysis that show that the most important direct causes are hemorrhage, hypertension, abortion, and sepsis; however, the proportion of deaths due to indirect causes is increasing in most parts of the world. The chapter then focuses on pregnancy-related complications, including nonfatal illnesses such as antenatal and postpartum depression, using the findings from systematic reviews conducted by the Child Health Epidemiology Reference Group. The most common contributors to maternal morbidity are probably anemia and depression at the community level, but prolonged and obstructed labor results in the highest burden of disease because of fistulas (IHME 2013). The chapter discusses the broader determinants of maternal morbidity and mortality, and then concludes by making the links with the interventions highlighted in chapter 7 in this volume (Gülmezoglu and others 2016).