Global report on preterm birth and stillbirth (1 of 7): definitions, description of the burden and opportunities to improve data

Abstract

Introduction: This is the first of seven articles from a preterm birth and stillbirth report. Presented here is an overview of the burden, an assessment of the quality of current estimates, review of trends, and recommendations to improve data.

Preterm birth: Few countries have reliable national preterm birth prevalence data. Globally, an estimated 13 million babies are born before 37 completed weeks of gestation annually. Rates are generally highest in low- and middle-income countries, and increasing in some middle- and high-income countries, particularly the Americas. Preterm birth is the leading direct cause of neonatal death (27%); more than one million preterm newborns die annually. Preterm birth is also the dominant risk factor for neonatal mortality, particularly for deaths due to infections. Long-term impairment is an increasing issue.

Stillbirth: Stillbirths are currently not included in Millennium Development Goal tracking and remain invisible in global policies. For international comparisons, stillbirths include late fetal deaths weighing more than 1000g or occurring after 28 weeks gestation. Only about 2% of all stillbirths are counted through vital registration and global estimates are based on household surveys or modelling. Two global estimation exercises reached a similar estimate of around three million annually; 99% occur in low- and middle-income countries. One million stillbirths occur during birth. Global stillbirth cause-of-death estimates are impeded by multiple, complex classification systems.

Recommendations to improve data: (1) increase the capture and quality of pregnancy outcome data through household surveys, the main data source for countries with 75% of the global burden; (2) increase compliance with standard definitions of gestational age and stillbirth in routine data collection systems; (3) strengthen existing data collection mechanisms--especially vital registration and facility data--by instituting a standard death certificate for stillbirth and neonatal death linked to revised International Classification of Diseases coding; (4) validate a simple, standardized classification system for stillbirth cause-of-death; and (5) improve systems and tools to capture acute morbidity and long-term impairment outcomes following preterm birth.

Conclusion: Lack of adequate data hampers visibility, effective policies, and research. Immediate opportunities exist to improve data tracking and reduce the burden of preterm birth and stillbirth.

Figure 1

Early and late neonatal mortality rates and under 5 mortality rates per 1000, 1960-2007. Source: Lawn, Kerber et al. [1]; Data from UN databases updated to 2007.

Figure 2

Causes of neonatal death globally based on estimates for 193 countries around the year 2000. Source: Reprinted from The Lancet, 365, Lawn JE, Cousens S, Zupan J, 4 million neonatal deaths: When? Where? Why?, 10, 2005, with permission from Elsevier. [2].

Figure 3

Percent distribution of neonatal causes of death by level of neonatal mortality showing the increasing proportion of neonatal deaths attributed to preterm birth with lower neonatal mortality rate. Source: Reprinted from The Lancet, 365, Lawn JE, Cousens S, Zupan J, 4 million neonatal deaths: When? Where? Why?, 10, 2005, with permission from Elsevier [2].

Figure 4

Estimated global number of stillbirths by world region, 2000. Source: Reprinted from The Lancet, 367, Stanton C, Lawn JE, Rahman H, Wilczynska-Ketende, K, Hill K, Stillbirth rates: delivering estimates in 190 countries, 8, 2006, with permission from Elsevier [7].

Figure 5

Data sources and methods for estimates of intrapartum stillbirth rates for 192 countries. Source: Reprinted from Bulleting of the World Health Organization, Lawn JE, Shibuya K, Stein C, No cry at birth: global estimates of intrapartum stillbirths and intrapartum-related neonatal deaths, 2005, with permission from WHO Press [56].

Figure 6

Classifi cation system for stillbirth cause-of-death. Source: Reprinted from BMC Pregnancy & Childbirth, Lawn JE, Yakoob YM, Haws, RA, Soomro T, Darmstadt GL, Bhutta ZA, 3.2 million stillbirths: epidemiology and overview of the evidence review, 2009, with permission from BMC [49]