New development of outcome measures

The EURO-PERISTAT project resulted from a recognition of the current limitations of the routine statistics produced across Europe.6 7 The aim of the project was to develop valid and reliable indicators for the monitoring and evaluation of perinatal health across the EU and involved 25 member states and Norway. National routine statistics were developed at a time when the majority of perinatal and neonatal deaths were of mature infants and associated with infection, poor maternal health and limited care provision. Nowadays, the main factor affecting neonatal survival is preterm delivery8 and, as such, comparative indicators should reflect this and be flexible enough to allow for the appropriate selection of birth cohorts to answer specific questions. In its latest report9 EURO-PERISTAT proposes a new approach for the reporting based on multiple indicators concerning outcomes, healthcare factors and other factors affecting pregnancy outcomes. However, much work is required across Europe to achieve this aim including the standardisation of birth and death notification or registration systems to include all births from 22 weeks' gestational age (including terminations of pregnancy) and coding systems, as well as the collection of all information necessary to produce their core indicators. Two such areas of work are highlighted: (1) the facilitation of data linkage between sources of birth and death data collection systems, and (2) the development of routine systems for the standardised collection of longer-term outcome data to measure maternal and neonatal morbidity. Collective action at the European level is necessary to ensure that the requisite legislative changes and support for standardised data collection are made in all EU countries to facilitate this approach.

Neonatal outcomes for preterm deliveries

Alongside the technological advances in neonatal medicine over recent years, neonatal mortality has shown a steady reduction. However, there has been a contemporaneous increase in the impact of very preterm infants of less than 33 weeks' gestation: these represent only approximately 2% of all births but account for over one-third of neonatal deaths. Wide variations are seen in the published survival rates for very preterm infants.10,–,13 Evans and Levene14 clearly illustrate, in their systematic review of preterm survival studies, that the most selective studies (ie, those only including admissions to neonatal intensive care) report significantly higher survival for the most preterm infants. In order to avoid such bias data should therefore be collected on the total birth cohort (live and stillbirths) for a geographically defined population. However, until recently there have been few population-based studies that fulfil these criteria for extremely preterm infants12 13 15 16 with published survival rates for both the total extreme preterm cohort as well as admissions for neonatal intensive care. The bias associated with studies of single-centre tertiary neonatal unit admissions13 when compared with geographically defined population studies17 can be seen in recent publications investigating the survival of extreme preterm infants where survival to discharge from neonatal care at 23 weeks' gestational age was 47% and 19% over similar time periods.

A series of gestational age and birth weight-specific survival charts has been produced for the geographically defined population covered by the Neonatal Survey, in the UK, for all birth outcomes for very preterm deliveries from 22 to 32 completed weeks' gestational age.18 19 To date these charts have been produced, for the use of clinicians and in their counselling of parents, to provide evidence for outcomes of (1) all fetuses known to be alive at the onset of labour, and (2) those admitted for neonatal care, with separate charts for ethnic group and sex of the fetus and the use of a simple algorithm for multiple pregnancies. Collection of the data for the EURO-PERISTAT indicators would facilitate the production of a regularly updated robust set of gestational age and birth weight-specific survival charts for all very preterm births in England and Wales.

The MOSAIC study (a standardised prospective birth cohort of very preterm infant across 10 European regions) shows variations in the classification of extreme preterm infants of less than 24 weeks' gestational age and how they can have a major impact on the mortality for various countries.16 This group propose a similar refinement: that the standard point of comparison should be to use all the ‘potential survivors’ defined as those alive at the onset of labour (or alive at the point of caesarean section) analysing the cohort by gestational age group. This eliminates the variation in registration rates caused by ethical and policy differences in those births at the limits of viability.20 21

Limitations of current data collection in England and Wales

Since part way through 2007 the data collection for the Confidential Enquiry into Maternal and Child Health (CEMACH)22 has limited its data collection to stillbirths and neonatal death—that is, excluding 22-week and 23-week late fetal losses, because of reduced funding. This exclusion means that UK perinatal mortality and stillbirth rates produced from the CEMACH data can no longer be adjusted to allow for direct comparison with international rates that use the WHO definition of the perinatal period from 22 weeks' gestation. In addition, there are no data to investigate variations in birth registration at the limits of viability that have an impact on neonatal mortality and preterm delivery rates. Birth registration definitions are limited to stillbirths as any liveborn infant should be registered as a live birth irrespective of the gestational age and weight at delivery and, as such, mortality following a live birth should not be affected. However, these definitional differences are known to also have an effect on the registration of live births with an under-registration of live births at a boundary when a stillbirth would not require reporting, possibly in a paternalistic effort to relieve parents of the burden of birth registration.2 Furthermore, recent discussions about the limits of viability in relation to the Abortion Act 1967 rely on complete data being available for infants born at around the lower gestational age of registration—that is, 24 weeks. Given the inherent inaccuracy in the routine calculation of gestational age and the need to investigate the survival of lower gestational age infants it is important to have data available about the viability for the total cohort of lower gestational age infants (22 and 23 weeks) to provide accurate gestational specific survival rates to ensure accurate monitoring of any improvement in outcomes within this group.

Population comparisons of neonatal outcomes require data to be collected that can help unravel whether the same standards are being used by all to determine whether an outcome is defined as a late fetal loss or stillbirth or labour ward death or admission for neonatal intensive care. Routine investigations into the variation in the rate of infants born at the limits of viability and their place of care (using the linkage of CEMACH data with study data to produce the total very preterm birth cohort), have shown as high as a threefold difference in the proportions of liveborn infants of 22–24 weeks' gestation admitted for neonatal intensive care compared to those who died on the labour ward across primary care trusts.23 These differences suggest a wide variation in proactive management of these infants that may account for some of the variation in subsequent neonatal mortality. The exclusion of late fetal loss data from CEMACH means that such investigations are no longer facilitated.

Longer-term morbidity outcomes

Information on late morbidity in survivors of neonatal intensive care is needed by several groups of people: by parents, so they can understand the possible consequences of survival in their baby and take informed decisions about their child's care; by the clinical team, for sharing with parents, for evaluating their service and for research; by commissioners of neonatal care and other services for children, so that they can make informed decisions and plans; and by the general public so they can take part in an informed debate on priorities in healthcare. Long-term follow-up for the early identification of disability and timely targeting of intervention is therefore required to monitor the outcomes for these children. Although official reports since 199224,–,27 have highlighted the need for neonatal units and health authorities to routinely collect late morbidity data, the data remain generally unavailable on a population basis or outside specialist centres. The EPICure study has, however, followed the 1995 UK cohort of extremely preterm survivors to 11 years of age28 and is currently assessing the 1996 cohort of extreme preterm birth survivors in England. Follow-up at 2 years of corrected age has been included as part of the National Neonatal Audit Data Set.29 Although the implementation of this is not yet established it should eventually provide routine information about the proportion of children alive with disability.