- Email: [email protected]
Social and Ethnic Inequalities in Infant Mortality: A Perspective from the United Kingdom
Social and Ethnic Inequalities in Infant Mortality: A Perspective from the United Kingdom Jennifer Hollowell, PhD, Jennifer J. Kurinczuk, MBChB, MSc, MD, Peter Brocklehurst, MBChB, MSc, and Ron Gray, MBChB, MPH Social inequalities in infant mortality can be clearly demonstrated in the countries of the United Kingdom with a social gradient between different groups. Marked variations in infant mortality between ethnic groups are also evident in England and Wales, with the highest rates seen in Pakistani and Caribbean infants and the lowest rates in the white and Bangladeshi groups. Although individual risk factors for infant mortality are well understood, the reasons why certain social and ethnic groups have higher rates remain to be fully elucidated. Policies and interventions to tackle these inequalities are likely to be most effective if they have both universal and targeted components to “level-up” rates to the rate of the most advantaged in society. Semin Perinatol 35:240-244 © 2011 Elsevier Inc. All rights reserved. KEYWORDS perinatal, infant mortality, inequalities, ethnicity, socioeconomic
H
ealth inequalities may be defined as “observable differences in health among individuals of different social groups.”1 In the United Kingdom, the social groupings based on socioeconomic position and on ethnic group membership have been used to stratify infant mortality data collected at the national level, and it is these groupings that we will concentrate upon in this report. Historically, infant mortality rates in the four countries of the United Kingdom (England, Wales, Scotland, and Northern Ireland) have followed a social gradient: rates are lowest in the most socioeconomically advantaged families, highest in the most socioeconomically disadvantaged, and lie inbetween the two for families with intermediate levels of disadvantage. This has been the case since infant mortality rates were first stratified in this way in the early 20th century. That such health inequalities take the form of a gradient implies that it is not only the poorest children whose health chances are compromised by their circumstances: children across society have poorer outcomes than those in the most advantaged circumstances. In addition, infant mortality rates in some ethnic minority groups living in the United Kingdom are higher than the rate in the overall population. Furthermore, variation between ethnic groups exists for prematurity and congenital anomaly rates which, as the commonest causes of neonatal deaths, might explain some of these differences in the infant mortality rates.
National Perinatal Epidemiology Unit, University of Oxford, Oxford, UK. Address reprint requests to Ron Gray, MBChB, MPH, National Perinatal Epidemiology Unit, University of Oxford, Old Rd Campus, Headington, Oxford OX3 7LF, UK. E-mail: [email protected]
240
0146-0005/11/$-see front matter © 2011 Elsevier Inc. All rights reserved. doi:10.1053/j.semperi.2011.02.021
Data on births and infant deaths in the United Kingdom are collected and reported at the national level, with statistics for England and Wales often aggregated. England and Wales together account for just more than 80% of the total population of the United Kingdom. In this work, we present a statistical overview of infant mortality and the variations in infant mortality rates between different social and ethnic groups in England and Wales.
Infant Mortality As illustrated in Fig. 1 the infant mortality rate in England and Wales has declined steadily during the past 3 decades, although the rate of decline from the early 1990s slowed markedly. The relative contribution of neonatal and postneonatal deaths has also changed during this period. In the 1980s, 58% of infant deaths occurred during the neonatal period (within the first 28 days after birth) with 42% in the postneonatal period (between 28 days and 1 year). From 1992 onwards, the distribution shifted to between 65% and 69% neonatal and 31%-35% postneonatal. This shift partially reflects the success of the “back-to-sleep” campaign that was associated with a two-thirds reduction in deaths attributable to sudden infant death syndrome (SIDS) between 1989 and 1993.2 Immaturity-related conditions and congenital anomalies are the 2 largest grouped causes of death and together accounted for three-quarters of infant deaths overall in 2007. In the neonatal period, immaturity related conditions alone accounted for 54% of deaths, whereas in the
Social and ethnic inequalities in infant mortality
Figure 1 Trends in infant, neonatal and postneonatal mortality rates, England and Wales, births 1980-2008. Data source: ONS, Mortality Statistics: Childhood, Infant, Perinatal series DH3.
postneonatal period the ranking was reversed with congenital anomalies accounting for 38% of deaths and 18% of deaths being attributable to immaturity.3
Socioeconomic Inequalities in Infant Mortality In many countries, including the countries of the United Kingdom, socioeconomic status is strongly associated with infant mortality. Socioeconomic status can be measured in various ways but a classification based on the father’s occupation is commonly used in the United Kingdom. Data on births and deaths in the United Kingdom are classified using the National Statistics Socioeconomic Classification (NSSEC). The NS-SEC has 17 categories, but many of these are small and hence are often aggregated into larger groups. Here, we present data for the following categories (the percentage of births in each group is shown in brackets): professional and managerial occupations (16%), intermediate occupations (37%), routine and manual occupations (35%), unclassified, including “never worked” and “long-term un-
Figure 2 Infant mortality rates by socio-economic position*, England and Wales (2007). *Classified using the NS-SEC. Data source: ONS, Mortality Statistics: Childhood, Infant, Perinatal series DH3 No, 40, Table 20.
241
Figure 3 Infant mortality by area deprivation quintile, England and Wales (1970-72) to 2004-2006. Data source: Norman et al (2008), Table 3.4
employed” (6%), and “sole registrants” (births registered solely by an unmarried mother, typically a lone parent) (7%). Infant mortality rates are lowest in the managerial and professional group (Fig. 2) and markedly higher in the children of fathers in routine and manual occupations and in the “unclassified” group. Rates are also high in the “sole registrant” group. The 3 groups with the highest rates (routine and manual, “unclassified,” and “sole registrants”) accounted for 47% of all births and 59% of all infant deaths in England and Wales in 2007. A socioeconomic gradient in infant mortality is also evident at an area level with the most deprived areas experiencing the highest levels of infant mortality. This is illustrated in Fig. 3, which shows time trends in infant mortality by quintiles of area deprivation based on an analysis by Norman et al.4 In this example, area deprivation is measured using the Townsend Index of Material Deprivation, which is calculated with small-area census data on unemployment levels, car ownership/access, levels of house ownership, and household overcrowding. Infant mortality exhibits a clear and persistent socioeconomic gradient, with the least deprived 20% of the population experiencing infant mortality rates varying from 21% to 55% lower than the most disadvantaged 20%. Interestingly, although overall infant mortality has declined across the period shown, inequality (the
Figure 4 Infant mortality by ethnic group, England and Wales (2005-06). Data source: ONS, Infant mortality by ethnic group, England and Wales (2005) (online edition) and Moser (2009).5 Data for 2005 and 2006 were pooled.
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Figure 5 ONS grouped cause-specific infant mortality rates by socioeconomic group (NS-SEC), England and Wales (2006-2007). Data source: ONS, Mortality Statistics: Childhood, Infant, Perinatal series DH3 Nos. 39 and 40, Table 12. Data for 2006 and 2007 were pooled.
gradient, ie, the slope of the line through the rate estimates) was at its lowest in the early 1980s and has since increased. Marked variations in infant mortality by ethnic group are also evident in England and Wales (Fig. 4).5 The greatest rates are seen in Pakistani and Caribbean infants and the lowest rates in the White and Bangladeshi groups. Black and Asian ethnic groups, which include African, Caribbean, Indian, Pakistani, and Bangladeshi groups, currently account for more than 14% of births in England and Wales.6 The pattern of infant mortality by ethnic group is not wholly explained by socioeconomic differences between groups: the parents of Bangladeshi infants, for example, have a similar socioeconomic profile to the parents of Pakistani infants suggesting that the relationship between infant mortality and ethnicity is influenced by a complex interplay of factors.7 Socioeconomic gradients in infant mortality for specific causes of death, grouped using the Office for National Statistics (ONS) cause of death groups (a hierarchical classification determined by the likely timing of the insult leading to death8), show subtly different patterns (Fig. 5). For example, SIDS, other causes and infections account for greater proportions of deaths in the “sole registrant” and “unclassified” groups. The distribution of cause of infant death also varies by ethnic group: Caribbean infants are at particularly high risk of death from immaturity-related conditions and SIDS, whereas congenital anomalies are the main cause of death amongst Pakistani infants (Fig. 6). The latter may result from a combination of an increased risk of genetic anomalies combined with lower access to prenatal screening in pregnancy and lower rates of termination of severely affected fetuses.
The Determinants of Infant Mortality and the Determinants of Inequalities in Infant Mortality Rates Three of the main causes of infant mortality are immaturityrelated conditions, congenital anomalies, and SIDS, with
each related to social position, ethnic grouping, and social exclusion. How can we explain these inequalities? The epidemiologist Geoffrey Rose9 argued cogently that we should distinguish between the determinants of individual cases of disease and the determinants of incidence rates of disease in populations. Although his argument was framed in terms of hypertension, it can be easily extended to infant mortality. The two distinct questions of interest become (1) why some children die in infancy and (2) why some populations have high infant mortality rates, whereas others have low rates. The answer to the first question is reasonably clear. There are certain risk factors that accumulate for an individual over time to increase their risk of infant mortality. These factors would include genetic conditions leading to lethal malformations, early gestational age at birth, exposure to smoking during and after pregnancy, maternal use of street drugs and excessive alcohol consumption during pregnancy, infant not sleeping on their back, and bed sharing (particularly with a parent using alcohol or drugs). The answer to the second
Figure 6 Main causes of death (ONS cause of death groups) by ethnic group, England and Wales (2005). Data source: ONS, Infant mortality by ethnic group, England and Wales (online edition).
Social and ethnic inequalities in infant mortality question is starting to become clearer. In certain groups there is a greater prevalence of some of these risk factors. For example, in the United Kingdom smoking during pregnancy is much more prevalent in low socioeconomic group, and therefore smoking may account for a sizeable proportion of the social inequality in infant mortality between rich and poor.10 However, it is then important to understand why women from disadvantaged social groups have a greater prevalence of smoking. This is still unclear but various explanations have been advanced.11,12 In addition to the risk factors that are known, various novel risk factors have been proposed, and it has been argued that these account for further variation in infant mortality rates between social groups which are not explained by more traditional risk factors. Thus, the insidious effects of discrimination and racism have been postulated to have an effect as well as psychobiological effects from the stresses of living in poverty.13,14 Although plausible, at present the contribution of these novel risk factors remains to be fully established. Irrespective of how the social inequalities actually arise, tackling them has been seen as a matter of social justice. Recently, the Strategic Review of Health Inequalities in England Post-2010 (known after its lead author as the Marmot Review)15 has reported and has suggested several policy objectives to address health inequalities in the United Kingdom. Of particular relevance to reducing inequalities in maternal and child health is the objective to give “every child the best start in life.” This emphasis on early childhood intervention has reenergized a raft of policies trying to improve health in early life and mirrors similar initiatives in the United States.16-18 Another central idea emphasized in the Marmot Review has been that rather than concentrate on certain social groups deemed to be at high risk, an approach is required to address the whole of the population. The report specifically states: Focusing solely on the most disadvantaged will not reduce health inequalities sufficiently. To reduce the steepness of the social gradient in health, actions must be universal, but with a scale and intensity that is proportionate to the level of disadvantage. The challenge for those working to reduce inequalities in maternal and child health in general and in infant mortality rates in particular is to develop services and public health interventions which can be tailored in just this way to level up the health of the population as a whole to the health of the social groups who fare best. Strategies to achieve this are likely to involve a combination of universal and targeted interventions. Examples of universal interventions would include provision of paid time-off to attend prenatal care appointments and ensuring adequate entitlement to child benefit and to paid maternity and paternity leave. Examples of more targeted strategies include approaches targeting deprived areas, for example, health action zones,19 or interventions to ensure improved access to health care for disadvantaged groups. Furthermore, effective strategies are likely to include actions to counter intervention-generated inequalities which arise because of differential uptake of services or
243 behavior change by less advantaged social groups and/or differential effectiveness of interventions in different social groups. For example, the “back to sleep” campaign to reduce SIDS, substantially reduced infant mortality attributable to SIDS in the United Kingdom but resulted in a widening socioeconomic differential in mortality.20 Strategies targeting socially patterned risk factors for infant mortality (and its main contributory causes) may also play a part: we have elsewhere collated the systematic review evidence on interventions targeting smoking during pregnancy and the postnatal period, overweight and obesity in pregnant and postnatal women and a range of infant risk factors for SIDS.21 It seems likely that any approach will have multiple components some universal, some targeted and involve a crosssectoral approach linking actions from several government departments and agencies working to support and empower women and families to improve their health and future life chances.
Acknowledgments This article is loosely based on an oral presentation given by R.G. to a workshop on Disparities in Perinatal Medicine at the Eunice Kennedy Shriver National Institute of Child Health and Human Development August 5-6, 2010. R.G. thanks the participants for constructive feedback. The article draws on work carried out and ideas developed as part of the inequalities in infant mortality project funded by the Department of Health. This is an independent report from a study that is funded by the Policy Research Programme in the Department of Health. The views expressed are not necessarily those of the department. Figure 3 is based on Crown copyright material published by Normal et al.4 and is reproduced under the terms of the Click-Use Public Sector Information (PSI) Licence C2011000011 and with the permission of the authors.
References 1. Harper S, Lynch J: Measuring health Inequalities, in Oakes JM, Kaufman JS (eds): Methods in Social Epidemiology San Francisco, John Wiley and Sons, 2006 2. Dwyer T, Ponsonby A-L: Sudden infant death syndrome: After the “back to sleep” campaign. BMJ 313:180-181, 1996 3. Kurinczuk JJ, Hollowell J, Brocklehurst P, et al: Inequalities in infant mortality briefing paper 1. Infant Mortality: Overview and Context: National Perinatal Epidemiology Unit, Oxford 2009. Available from: http://www.npeu.ox.ac.uk/infant-mortality. Accessed March 17, 2011 4. Norman PP, Gregory IP, Dorling DD, et al: Geographical trends in infant mortality: England and Wales, 1970-2006. Health Statistics Q 40:18-29, 2008 5. Moser K: Gestation-specific infant mortality by social and biological factors among babies born in England and Wales in 2006. Health Statistics Q 42:78-87, 2009 6. Moser K, Stanfield KM, Leon DA: Birthweight and gestational age by ethnic group, England and Wales 2005: Introducing new data on births. Health Statistics Q 39:22-31, 2008 7. Gray R, Headley J, Oakley L, et al: Inequalities in Infant Mortality Project Briefing paper 3. Towards an understanding of variations in infant mortality between different ethnics groups in England and Wales. National Perinatal Epidemiology Unit, Oxford 2009. Available
J. Hollowell et al
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8.
9. 10.
11.
12. 13. 14.
15.
from: http://www.npeu.ox.ac.uk/infant-mortality. Accessed March 17, 2011 Alberman E, Botting B, Blatchley N, et al: A new hierarchical classification of causes of infant deaths in England and Wales. Arch Dis Child 70:403-409, 1994 Rose G: Sick individuals and sick populations. Int J Epidemiol 14:3238, 1985 Gray R, Bonellie SR, Chalmers J, et al: Contribution of smoking during pregnancy to inequalities in stillbirth and infant death in Scotland 1994-2003: Retrospective population based study using hospital maternity records. BMJ 339:b3754, 2009 Chilcoat HD: An overview of the emergence of disparities in smoking prevalence, cessation, and adverse consequences among women. Drug Alcohol Depend 104:S17-S23, 2009 Graham H: Women and smoking: Understanding socioeconomic influences. Drug Alcohol Depend 104:S11-S16, 2009 Kramer MR, Hogue CR: What causes racial disparities in very preterm birth? A biosocial perspective. Epidemiol Rev 31:84-98, 2009 Rich-Edwards JW, Grizzard TA: Psychosocial stress and neuroendocrine mechanisms in preterm delivery. Am J Obstet Gynecol 192:S30S35, 2005 Strategic Review of Health Inequalities in England Post-2010: Fair So-
16.
17.
18.
19. 20.
21.
ciety, Health Lives. Marmot Review Final Report. London, University College London (UCL), 2010 Doyle O, Harmon CP, Heckman JJ, et al: Investing in early human development: Timing and economic efficiency. Econ Hum Biol 7:1-6, 2009 Kitzman HJ, Olds DL, Cole RE, et al: Enduring effects of prenatal and Infancy Home Visiting by nurses on children: Follow-up of a randomized trial among children at Age 12 years. Arch Pediatr Adolesc Med 164:412-418, 2010 Gray R, McCormick MC: Early Childhood intervention programs in the US: Recent Advances and Future Recommendations. J Prim Prev 26: 259-275, 2005 Mackenbach JP, Bakker MJ: Tackling socioeconomic inequalities in health: Analysis of European experiences. Lancet 362:1409-1414, 2003 Blair PS, Sidebotham P, Berry PJ, et al: Major epidemiological changes in sudden infant death syndrome: A 20-year population-based study in the UK. Lancet 367:314-319, 2006 Allen F, Gray R, Oakley L, et al: Inequalities in Infant Mortality Project Evidence Map Report 4. Interventions targeting major potentially modifiable risk factors for infant mortality: a user’s guide to the systematic review evidence. National Perinatal Epidemiology Unit, Oxford 2009. Available from: http://www.npeu.ox.ac.uk/infantmortality. Accessed March 17, 2011
H
ealth inequalities may be defined as “observable differences in health among individuals of different social groups.”1 In the United Kingdom, the social groupings based on socioeconomic position and on ethnic group membership have been used to stratify infant mortality data collected at the national level, and it is these groupings that we will concentrate upon in this report. Historically, infant mortality rates in the four countries of the United Kingdom (England, Wales, Scotland, and Northern Ireland) have followed a social gradient: rates are lowest in the most socioeconomically advantaged families, highest in the most socioeconomically disadvantaged, and lie inbetween the two for families with intermediate levels of disadvantage. This has been the case since infant mortality rates were first stratified in this way in the early 20th century. That such health inequalities take the form of a gradient implies that it is not only the poorest children whose health chances are compromised by their circumstances: children across society have poorer outcomes than those in the most advantaged circumstances. In addition, infant mortality rates in some ethnic minority groups living in the United Kingdom are higher than the rate in the overall population. Furthermore, variation between ethnic groups exists for prematurity and congenital anomaly rates which, as the commonest causes of neonatal deaths, might explain some of these differences in the infant mortality rates.
National Perinatal Epidemiology Unit, University of Oxford, Oxford, UK. Address reprint requests to Ron Gray, MBChB, MPH, National Perinatal Epidemiology Unit, University of Oxford, Old Rd Campus, Headington, Oxford OX3 7LF, UK. E-mail: [email protected]
240
0146-0005/11/$-see front matter © 2011 Elsevier Inc. All rights reserved. doi:10.1053/j.semperi.2011.02.021
Data on births and infant deaths in the United Kingdom are collected and reported at the national level, with statistics for England and Wales often aggregated. England and Wales together account for just more than 80% of the total population of the United Kingdom. In this work, we present a statistical overview of infant mortality and the variations in infant mortality rates between different social and ethnic groups in England and Wales.
Infant Mortality As illustrated in Fig. 1 the infant mortality rate in England and Wales has declined steadily during the past 3 decades, although the rate of decline from the early 1990s slowed markedly. The relative contribution of neonatal and postneonatal deaths has also changed during this period. In the 1980s, 58% of infant deaths occurred during the neonatal period (within the first 28 days after birth) with 42% in the postneonatal period (between 28 days and 1 year). From 1992 onwards, the distribution shifted to between 65% and 69% neonatal and 31%-35% postneonatal. This shift partially reflects the success of the “back-to-sleep” campaign that was associated with a two-thirds reduction in deaths attributable to sudden infant death syndrome (SIDS) between 1989 and 1993.2 Immaturity-related conditions and congenital anomalies are the 2 largest grouped causes of death and together accounted for three-quarters of infant deaths overall in 2007. In the neonatal period, immaturity related conditions alone accounted for 54% of deaths, whereas in the
Social and ethnic inequalities in infant mortality
Figure 1 Trends in infant, neonatal and postneonatal mortality rates, England and Wales, births 1980-2008. Data source: ONS, Mortality Statistics: Childhood, Infant, Perinatal series DH3.
postneonatal period the ranking was reversed with congenital anomalies accounting for 38% of deaths and 18% of deaths being attributable to immaturity.3
Socioeconomic Inequalities in Infant Mortality In many countries, including the countries of the United Kingdom, socioeconomic status is strongly associated with infant mortality. Socioeconomic status can be measured in various ways but a classification based on the father’s occupation is commonly used in the United Kingdom. Data on births and deaths in the United Kingdom are classified using the National Statistics Socioeconomic Classification (NSSEC). The NS-SEC has 17 categories, but many of these are small and hence are often aggregated into larger groups. Here, we present data for the following categories (the percentage of births in each group is shown in brackets): professional and managerial occupations (16%), intermediate occupations (37%), routine and manual occupations (35%), unclassified, including “never worked” and “long-term un-
Figure 2 Infant mortality rates by socio-economic position*, England and Wales (2007). *Classified using the NS-SEC. Data source: ONS, Mortality Statistics: Childhood, Infant, Perinatal series DH3 No, 40, Table 20.
241
Figure 3 Infant mortality by area deprivation quintile, England and Wales (1970-72) to 2004-2006. Data source: Norman et al (2008), Table 3.4
employed” (6%), and “sole registrants” (births registered solely by an unmarried mother, typically a lone parent) (7%). Infant mortality rates are lowest in the managerial and professional group (Fig. 2) and markedly higher in the children of fathers in routine and manual occupations and in the “unclassified” group. Rates are also high in the “sole registrant” group. The 3 groups with the highest rates (routine and manual, “unclassified,” and “sole registrants”) accounted for 47% of all births and 59% of all infant deaths in England and Wales in 2007. A socioeconomic gradient in infant mortality is also evident at an area level with the most deprived areas experiencing the highest levels of infant mortality. This is illustrated in Fig. 3, which shows time trends in infant mortality by quintiles of area deprivation based on an analysis by Norman et al.4 In this example, area deprivation is measured using the Townsend Index of Material Deprivation, which is calculated with small-area census data on unemployment levels, car ownership/access, levels of house ownership, and household overcrowding. Infant mortality exhibits a clear and persistent socioeconomic gradient, with the least deprived 20% of the population experiencing infant mortality rates varying from 21% to 55% lower than the most disadvantaged 20%. Interestingly, although overall infant mortality has declined across the period shown, inequality (the
Figure 4 Infant mortality by ethnic group, England and Wales (2005-06). Data source: ONS, Infant mortality by ethnic group, England and Wales (2005) (online edition) and Moser (2009).5 Data for 2005 and 2006 were pooled.
J. Hollowell et al
242
Figure 5 ONS grouped cause-specific infant mortality rates by socioeconomic group (NS-SEC), England and Wales (2006-2007). Data source: ONS, Mortality Statistics: Childhood, Infant, Perinatal series DH3 Nos. 39 and 40, Table 12. Data for 2006 and 2007 were pooled.
gradient, ie, the slope of the line through the rate estimates) was at its lowest in the early 1980s and has since increased. Marked variations in infant mortality by ethnic group are also evident in England and Wales (Fig. 4).5 The greatest rates are seen in Pakistani and Caribbean infants and the lowest rates in the White and Bangladeshi groups. Black and Asian ethnic groups, which include African, Caribbean, Indian, Pakistani, and Bangladeshi groups, currently account for more than 14% of births in England and Wales.6 The pattern of infant mortality by ethnic group is not wholly explained by socioeconomic differences between groups: the parents of Bangladeshi infants, for example, have a similar socioeconomic profile to the parents of Pakistani infants suggesting that the relationship between infant mortality and ethnicity is influenced by a complex interplay of factors.7 Socioeconomic gradients in infant mortality for specific causes of death, grouped using the Office for National Statistics (ONS) cause of death groups (a hierarchical classification determined by the likely timing of the insult leading to death8), show subtly different patterns (Fig. 5). For example, SIDS, other causes and infections account for greater proportions of deaths in the “sole registrant” and “unclassified” groups. The distribution of cause of infant death also varies by ethnic group: Caribbean infants are at particularly high risk of death from immaturity-related conditions and SIDS, whereas congenital anomalies are the main cause of death amongst Pakistani infants (Fig. 6). The latter may result from a combination of an increased risk of genetic anomalies combined with lower access to prenatal screening in pregnancy and lower rates of termination of severely affected fetuses.
The Determinants of Infant Mortality and the Determinants of Inequalities in Infant Mortality Rates Three of the main causes of infant mortality are immaturityrelated conditions, congenital anomalies, and SIDS, with
each related to social position, ethnic grouping, and social exclusion. How can we explain these inequalities? The epidemiologist Geoffrey Rose9 argued cogently that we should distinguish between the determinants of individual cases of disease and the determinants of incidence rates of disease in populations. Although his argument was framed in terms of hypertension, it can be easily extended to infant mortality. The two distinct questions of interest become (1) why some children die in infancy and (2) why some populations have high infant mortality rates, whereas others have low rates. The answer to the first question is reasonably clear. There are certain risk factors that accumulate for an individual over time to increase their risk of infant mortality. These factors would include genetic conditions leading to lethal malformations, early gestational age at birth, exposure to smoking during and after pregnancy, maternal use of street drugs and excessive alcohol consumption during pregnancy, infant not sleeping on their back, and bed sharing (particularly with a parent using alcohol or drugs). The answer to the second
Figure 6 Main causes of death (ONS cause of death groups) by ethnic group, England and Wales (2005). Data source: ONS, Infant mortality by ethnic group, England and Wales (online edition).
Social and ethnic inequalities in infant mortality question is starting to become clearer. In certain groups there is a greater prevalence of some of these risk factors. For example, in the United Kingdom smoking during pregnancy is much more prevalent in low socioeconomic group, and therefore smoking may account for a sizeable proportion of the social inequality in infant mortality between rich and poor.10 However, it is then important to understand why women from disadvantaged social groups have a greater prevalence of smoking. This is still unclear but various explanations have been advanced.11,12 In addition to the risk factors that are known, various novel risk factors have been proposed, and it has been argued that these account for further variation in infant mortality rates between social groups which are not explained by more traditional risk factors. Thus, the insidious effects of discrimination and racism have been postulated to have an effect as well as psychobiological effects from the stresses of living in poverty.13,14 Although plausible, at present the contribution of these novel risk factors remains to be fully established. Irrespective of how the social inequalities actually arise, tackling them has been seen as a matter of social justice. Recently, the Strategic Review of Health Inequalities in England Post-2010 (known after its lead author as the Marmot Review)15 has reported and has suggested several policy objectives to address health inequalities in the United Kingdom. Of particular relevance to reducing inequalities in maternal and child health is the objective to give “every child the best start in life.” This emphasis on early childhood intervention has reenergized a raft of policies trying to improve health in early life and mirrors similar initiatives in the United States.16-18 Another central idea emphasized in the Marmot Review has been that rather than concentrate on certain social groups deemed to be at high risk, an approach is required to address the whole of the population. The report specifically states: Focusing solely on the most disadvantaged will not reduce health inequalities sufficiently. To reduce the steepness of the social gradient in health, actions must be universal, but with a scale and intensity that is proportionate to the level of disadvantage. The challenge for those working to reduce inequalities in maternal and child health in general and in infant mortality rates in particular is to develop services and public health interventions which can be tailored in just this way to level up the health of the population as a whole to the health of the social groups who fare best. Strategies to achieve this are likely to involve a combination of universal and targeted interventions. Examples of universal interventions would include provision of paid time-off to attend prenatal care appointments and ensuring adequate entitlement to child benefit and to paid maternity and paternity leave. Examples of more targeted strategies include approaches targeting deprived areas, for example, health action zones,19 or interventions to ensure improved access to health care for disadvantaged groups. Furthermore, effective strategies are likely to include actions to counter intervention-generated inequalities which arise because of differential uptake of services or
243 behavior change by less advantaged social groups and/or differential effectiveness of interventions in different social groups. For example, the “back to sleep” campaign to reduce SIDS, substantially reduced infant mortality attributable to SIDS in the United Kingdom but resulted in a widening socioeconomic differential in mortality.20 Strategies targeting socially patterned risk factors for infant mortality (and its main contributory causes) may also play a part: we have elsewhere collated the systematic review evidence on interventions targeting smoking during pregnancy and the postnatal period, overweight and obesity in pregnant and postnatal women and a range of infant risk factors for SIDS.21 It seems likely that any approach will have multiple components some universal, some targeted and involve a crosssectoral approach linking actions from several government departments and agencies working to support and empower women and families to improve their health and future life chances.
Acknowledgments This article is loosely based on an oral presentation given by R.G. to a workshop on Disparities in Perinatal Medicine at the Eunice Kennedy Shriver National Institute of Child Health and Human Development August 5-6, 2010. R.G. thanks the participants for constructive feedback. The article draws on work carried out and ideas developed as part of the inequalities in infant mortality project funded by the Department of Health. This is an independent report from a study that is funded by the Policy Research Programme in the Department of Health. The views expressed are not necessarily those of the department. Figure 3 is based on Crown copyright material published by Normal et al.4 and is reproduced under the terms of the Click-Use Public Sector Information (PSI) Licence C2011000011 and with the permission of the authors.
References 1. Harper S, Lynch J: Measuring health Inequalities, in Oakes JM, Kaufman JS (eds): Methods in Social Epidemiology San Francisco, John Wiley and Sons, 2006 2. Dwyer T, Ponsonby A-L: Sudden infant death syndrome: After the “back to sleep” campaign. BMJ 313:180-181, 1996 3. Kurinczuk JJ, Hollowell J, Brocklehurst P, et al: Inequalities in infant mortality briefing paper 1. Infant Mortality: Overview and Context: National Perinatal Epidemiology Unit, Oxford 2009. Available from: http://www.npeu.ox.ac.uk/infant-mortality. Accessed March 17, 2011 4. Norman PP, Gregory IP, Dorling DD, et al: Geographical trends in infant mortality: England and Wales, 1970-2006. Health Statistics Q 40:18-29, 2008 5. Moser K: Gestation-specific infant mortality by social and biological factors among babies born in England and Wales in 2006. Health Statistics Q 42:78-87, 2009 6. Moser K, Stanfield KM, Leon DA: Birthweight and gestational age by ethnic group, England and Wales 2005: Introducing new data on births. Health Statistics Q 39:22-31, 2008 7. Gray R, Headley J, Oakley L, et al: Inequalities in Infant Mortality Project Briefing paper 3. Towards an understanding of variations in infant mortality between different ethnics groups in England and Wales. National Perinatal Epidemiology Unit, Oxford 2009. Available
J. Hollowell et al
244
8.
9. 10.
11.
12. 13. 14.
15.
from: http://www.npeu.ox.ac.uk/infant-mortality. Accessed March 17, 2011 Alberman E, Botting B, Blatchley N, et al: A new hierarchical classification of causes of infant deaths in England and Wales. Arch Dis Child 70:403-409, 1994 Rose G: Sick individuals and sick populations. Int J Epidemiol 14:3238, 1985 Gray R, Bonellie SR, Chalmers J, et al: Contribution of smoking during pregnancy to inequalities in stillbirth and infant death in Scotland 1994-2003: Retrospective population based study using hospital maternity records. BMJ 339:b3754, 2009 Chilcoat HD: An overview of the emergence of disparities in smoking prevalence, cessation, and adverse consequences among women. Drug Alcohol Depend 104:S17-S23, 2009 Graham H: Women and smoking: Understanding socioeconomic influences. Drug Alcohol Depend 104:S11-S16, 2009 Kramer MR, Hogue CR: What causes racial disparities in very preterm birth? A biosocial perspective. Epidemiol Rev 31:84-98, 2009 Rich-Edwards JW, Grizzard TA: Psychosocial stress and neuroendocrine mechanisms in preterm delivery. Am J Obstet Gynecol 192:S30S35, 2005 Strategic Review of Health Inequalities in England Post-2010: Fair So-
16.
17.
18.
19. 20.
21.
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