Rising infant mortality figures in England and Wales - the need to understand gestation-specific mortality
Whilst there are many legitimate concerns regarding the state of child health in the UK (BMJ 2018;360:k1270), including those of the Royal College of Paediatric and Child Health (RCPCH) and its new president (BMJ 2018;360:k1116), the latest figures from the Office for National Statistics (ONS), reporting rises in infant mortality rates in 2015 and 2016, (1) require a more detailed analysis before being highlighted as part of this overall picture.
Infant mortality rates are calculated by combining the neonatal (0 - 28 days) and post-neonatal mortality rates (4 weeks – 1 year). Within the latest ONS figures for England and Wales, it is clear that post-neonatal mortality rates have fallen consistently in the 30 years to 2016, likely secondary to changes in immunisation schedules, and improvements in paediatric clinical practice and provision, including paediatric critical care.
Neonatal mortality rates similarly fell over the same period until 2014, but started to rise again in 2015 and 2016. However even within these figures, the rise in mortality noted is related solely to greater numbers of deaths being reported within the first day of life. One of the major causes for this would appear to be related to increasing numbers of “live births” being included at, or even below, the extremes of viability. Survival amongst babies born at 22 and 23 weeks gestation is no longer exceptional, with almost one third of babies born at this gestation surviving the neonatal period in 2015 (2), although mortality rates remain high. ONS-reported numbers of live born infants of 22 weeks gestation or less (many of whom are pre-viable) have shown a considerable increase over the 3 years in question (2014: 376; 2015: 427; 2016: 545), clearly impacting on the reported mortality rates.
The reasons for the increasing number of “live births” below 23 weeks requires further investigation, especially given its potential impact on the overall infant mortality figures, which are often used as wider indicators of both societal and healthcare system issues. It may simply relate to more recent changes in obstetric and neonatal practice, where babies born at these gestations are now more regularly observed for signs of life, before decisions regarding on-going care are made, to recent coroners’ directives that any baby born with a detectable heartbeat should be considered a “live birth” whatever the gestation, or to other factors, such as increasing numbers of pregnancies occurring with assisted reproduction technology.
Concerns over differences in local, national and international registration practices around extremely preterm birth limit the uses of routine data for between unit, national and international comparisons. Gestation-specific mortality rates would allow for a more informed accurate monitoring of mortality rates over time and, if accepted internationally, provide direct comparisons between “High Income Countries” (HICs). The Europeristat group have recently suggested that routine data should exclude those of less than 24 weeks gestation (as well as terminations of pregnancy) to facilitate the continued surveillance of preterm birth in HICs (2). MBRRACE-UK data have been produced using these exclusion since 2013, and provide such data for all countries of the UK. (2, 4, 5)
Whilst mortality may seem relatively easy to measure, when rates are comparatively low, it may not be the most accurate indicator, because as the ONS statistics demonstrate, differences in a small number of individuals may have significant effects on overall figures, both when compared over time and with other countries. Establishing an international gestation-specific standard to minimise reporting and registration differences is essential to provide a more accurate indicator.
2. Manktelow BN, Smith LK, Prunet C, Smith PW, Boby T, Hyman-Taylor P, Kurinczuk JJ, Field DJ, Draper ES, on behalf of the MBRRACE-UK Collaboration. MBRRACE-UK Perinatal Mortality Surveillance Report, UK. Perinatal Deaths for Births from January to December 2015. Leicester: The Infant Mortality and Morbidity Studies, Department of Health Sciences, University of Leicester. 2017 ISBN: 978-0-9935059-5-9
3. Delnord M, Hindori-Mohangoo AD, Smith LK et al. Variations in very preterm birth rates in 30 high-income countries: are valid international comparisons possible with routine data? BJOG 2017; 124: 785-794
4. Manktelow BM, Smith LK, Evans TA, Hyman-Taylor P, Kurinczuk JJ, Field DJ, Smith PW, Draper ES, on behalf of the MBRRACE-UK collaboration. Perinatal Mortality Surveillance Report UK Perinatal Deaths for births from January to December 2013. Leicester: The Infant Mortality and Morbidity Group, Department of Health Sciences, University of Leicester. 2015.
5. Manktelow BN, Smith LK, Seaton SE, Hyman-Taylor P, Kurinczuk JJ, Field DJ, Smith PW, Draper ES, on behalf of the MBRRACE-UK Collaboration. MBRRACE-UK Perinatal Mortality Surveillance Report, UK Perinatal Deaths for Births from January to December 2014. Leicester: The Infant Mortality and Morbidity Studies, Department of Health Sciences, University of Leicester. 2016. ISBN: 978-0-9935059-4-2
Competing interests: No competing interests