Economic consequences of preterm birth and low birthweight Stavros Petrou The high rates of mortality and morbidity arising from preterm birth and low birthweight impose an immense burden on the health, education and social services and on families. This was evaluated in several economic studies published in the 1970s and early 1980s, but an ability to intervene effectively to increase survival has transformed neonatal care over the past two decades. In addition, the relative prices of resource inputs are vastly different. This paper surveys the scientific literature on the economic consequences of preterm birth and low birthweight, including: (1) studies, which estimate the economic costs of the conditions and (2) economic evaluations of primary and secondary prevention and treatment strategies. This paper summarises the scope and scientific quality of the published evidence, identifies gaps in our knowledge and considers the future research agenda in this area. INTRODUCTION Although the numbers of live births registered in most industrialised nations have remained relatively stable in recent years, the incidence of preterm birth and low birth- weight has increased. In England and Wales, for example, the percentage of liveborn babies weighing 2500 g and less increased from 6.79% in 1990 to 7.28% in 1996 1 . The reported incidence of very small babies has increased at a faster rate. For example, the percentage of liveborn babies weighing less than 1500 g in England and Wales increased from 0.96% in 1990 to 1.22% in 1996 and that of liveborn babies weighing less than 1000 g from 0.34% to 0.49% 1 . Similar trends have been noted in other industrialised nations 2 . Furthermore, advances in perinatal practices, such as increased use of assisted ventilation in the delivery room and surfactant therapy, have improved the chances for sur- vival of low gestational age and birthweight infants. A recent review of the world literature, revealed that at 23 weeks ges- tation, survival ranged from 2% to 35%. At 24 weeks gesta- tion the range was 17% to 58%, and at 25 weeks gestation 35% to 85% 3 . The large variations in survival rates are large- ly explained by differences in population descriptors, in the initiation and withdrawal of treatment, and the duration of survival considered. Nevertheless, a consistent upward trend in survival rates has been noted, particularly during the 1990s 3 . The increasing incidence and improved survival chances of infants of low gestational age and birthweight, combined with the diffusion of new technologies, have increased the demand for and cost of care provided to these infants during the neonatal period and in later life. This is reflected, in part, in national trends in resources for neonatal care 1 and in macroeconomic estimates of conditions originating in the perinatal period 2 . This paper surveys the scientific literature on the economic consequences of preterm birth and low birthweight for the health services, for other sectors of the economy, and for families and carers. In so doing, it high- lights gaps in our current knowledge of the topic and identifies requirements for further research in this area. METHODOLOGICAL CONSIDERATIONS Consideration of the economic consequences of preterm birth and low birthweight requires elucidation of a number of methodological issues. The majority of studies that have estimated the economic consequences of preterm birth or low birthweight have tended to focus on their economic costs. In theory, this should involve considering the bene- fits or social sacrifices foregone by caring for these infants, referred to by economists as opportunity costs. However, as an operational standard, economists have tended to focus on the market prices of resource inputs entailed by the care process. The economic costs of the care process can broadly be divided into direct costs and indirect costs. Direct costs represent the resources purchased directly as a result of the healthcare activity. Indirect costs, on the other hand, represent the element of indirect consumption of resources in the production process, for example the value of lost earnings by patients or carers of patients who are unable to work as a result of the healthcare activity. The process of measuring the economic costs of preterm birth and low birthweight can encompass a variety of methods of varying degrees of complexity. The most com- mon alternative approaches are based on cost accounting methods, either using detailed information about resources used by individual patients (the ‘bottom up’ approach), or by BJOG: an International Journal of Obstetrics and Gynaecology April 2003, Vol. 110 (Suppl 20), pp. 17--23 D RCOG 2003 BJOG: an International Journal of Obstetrics and Gynaecology doi:10.1016/S1470-0328(03)00013-2 www.bjog-elsevier.com National Perinatal Epidemiology Unit, Institute of Health Sciences, University of Oxford, Oxford, UK Correspondence: Dr S. Petrou, National Perinatal Epidemiology Unit, Institute of Health Sciences, University of Oxford, Old Road, Headington, Oxford OX3 7LF, UK.