Early neonatal sudden unexpected unexplained deaths (for which we use the term ENSUD) have not been subject to detailed study. The authors investigated the incidence from 1983 to 2007 in the population of the North East of England and North Cumbria. The authors found 30 cases of unexplained ENSUD, giving an overall rate of 0.35/10 000 live births, with no significant change in incidence over this time, and they identified a further 19 deaths of abandoned babies. The authors conclude that unexplained ENSUD is even more rare than has been appreciated and its incidence has not been altered by the considerable changes in maternity care over the last 25 years.
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Early neonatal sudden unexpected unexplained deaths (ENSUD) in term or near term babies are rare events. The only population based data are old (1977–1979) and reported a rate in Sweden of deaths occurring between 6 and 100 h after birth of 1.2 deaths per 10 000 live births.1 These deaths have not been well characterised, unlike sudden unexpected deaths in infancy (SUDI). Studies of SUDI have generally excluded deaths in infants aged under 1 week, and the recently published work on child deaths from the Confidential Enquiry into Maternal and Child Health excluded all deaths under 28 days.2
This population based study aimed to ascertain cases of unexplained ENSUD in infants ≥34 weeks gestation in the North East and North Cumbria between January 1983 and December 2007. We wished to examine the events leading to death, the place of death (whether at home or in the hospital) and any factors contributing to the death. We also aimed to examine any evidence for changes in the nature or timing of these deaths over this period of time, as changes in practice, such as decreasing lengths of postnatal stay, might affect rates of these deaths. In doing this work we noted that a proportion of unexplained deaths were abandoned babies, which we also report.
We used the Perinatal Mortality Survey (PMS) at the Regional Maternity Survey Office in Newcastle upon Tyne3 to ascertain cases from January 1983 to December 2007 in the North East and North Cumbria. The PMS captures all fetal loss from 20 weeks of gestation, all stillbirths and all deaths up to the first postnatal year. In addition to standard data fields, the database includes narrative material such as autopsy reports, summary clinical letters and related documents. The PMS was developed with permission from the ethics committee of the then Northern Regional Health Authority.
What is already known on this topic
▶ Early neonatal sudden unexpected death is rare.
▶ Maternity practices in the UK have changed much over the last 25 years.
What this study adds
▶ Early neonatal sudden unexpected unexplained deaths are even more rare than the literature suggests.
▶ There is no evidence that changes in maternity practices over the last 25 years have impacted on rates of unexplained ENSUD.
We included infants of ≥34 weeks' gestation, born in good condition and without other illness or congenital anomaly that died suddenly and unexpectedly within the first postnatal week, and were not considered to have a full pathological explanation for the death. We chose this lower gestation limit because we thought that some of these cases might be related to a mild degree of prematurity, and in one large service these babies are mostly looked after on the postnatal wards. We defined ‘good condition’ as having Apgar scores of 7 or more at 5 min with no evidence of resuscitation beyond suction of the airway. We excluded babies who were found to have congenital anomalies at autopsy that were considered to have accounted for the death, and all other early neonatal deaths fully accounted for by clinical or autopsy findings.
The place of death was taken from the database. However, three infants who were recorded as having died in hospital were reclassified based on the clinical history of being found lifeless at home. As attempts at resuscitation were unsuccessful we considered these infants to have been dead before arrival at hospital.
We recorded maternal age, parity and past medical history; obstetric history including mode of delivery; baby sex, gestation, birth weight, condition at birth and mode of feeding; and events leading to death, place of death and postmortem findings.
We divided the timeline into 5-year epochs to examine temporal trends. Incidences were calculated from numbers of live births. We used the χ2 test to calculate the statistical significance of any differences in the rates of events over the five quinquennia.
We identified 30 infants with unexplained ENSUD out of 828 648 live births (0.35 per 10 000). All were singletons with gestations of 35 to 40 weeks (median 38) and mean birth weight 3071 g. The maternal age ranged between 17 and 38 years. Three died before 2 h, and a further 4 by 24 h. In all, 28/30 had died by 120 h (5 days). We found no relation to sex, gestation or mode of delivery. Although there were generally fewer of these deaths in the more recent quinquennia, this did not reach statistical significance (table 1). There was no over-representation of less mature babies.
For two babies, autopsies were not permitted by the parents and apparently not mandated by a Coroner. Of those with autopsies, 14 did not have any abnormal findings but an equal proportion had findings that were judged at the time not to have been sufficient explanations for the deaths. Evidence for possible underlying metabolic defects was found in five babies: fatty liver in three, evidence of hypoglycemia before death in one, and an abnormal acyl-carnitine profile in another, but no further details of this abnormality could be ascertained.
Seventeen infants died in hospital. Of these, 13 occurred in the postnatal ward, three on delivery suite and one occurred in Special Care. Thirteen died at home, of which 10 presented as ‘cot death’ with the infant found lifeless. There was no significant trend in the relative proportions dying at home or in hospital over time. Defining the working day as 08:00–18:00, the deaths at home were evenly balanced between these times and out of hours (seven and six respectively), but those in hospital were much more likely to occur out of hours (15 and two respectively).
Despite the death occurring suddenly and apparently unexpectedly, nine of the infants showed some clinical signs over the hours before their death. Seven suddenly deteriorated with bradycardia, turning pale and apnoeic while witnessed by their mothers. Twelve showed no warning signs before being found dead.
Eight infants presented dead or collapsed on the breast, all born to primiparous mothers. Four of these were found dead at the breast after both mother and child fell asleep after a feed. Four of the six of these deaths which occurred in the hospital were in the early hours of the morning. It is possible that two of these babies may have had an underlying metabolic disorder.
We identified a further 19 babies (0.23 per 10 000), all of which were abandoned following an unattended birth. These pregnancies were typically concealed and the infants found in various states of decomposition. Of these, eight were known to be born to mothers <18 years, five were born to mothers ≥18 years and for the remaining six, mothers were unidentified. All had autopsies, and all were estimated by the pathologist to have been born at term. There was no trend in incidence over the 25 years.
This is by far the largest population based study of any yet published on unexplained ENSUD, and includes babies for whom the death occurred at home as well as in hospital. We have found that unexplained ENSUD is very rare, at just 0.35 per 10 000 live births, which is much lower than other authors have reported (table 2). We found no significant change in incidence over the 25 years despite improvements in the quality of autopsies and changes in midwifery practice such as shortening of the length of stay in hospital. Half of the babies had suggestive, but not diagnostic findings at autopsy; it may be that with modern techniques, fewer of these babies would be regarded as not having an adequate pathological cause for the death, especially where metabolic disease is a possibility, so it is possible that the decline in incidence is genuine even though not statistically significant, and reflects improved techniques rather than fewer ENSUD.4
The 19 abandoned babies may represent the outcomes of a heterogeneous group of vulnerable women in a variety of situations: possibilities might be women or girls who did not realise they were pregnant, could not cope with the situation, or had significant mental health or learning disability. It is notable that of the 19 infants, at least eight were born to children <18 years old. Furthermore, the 19 we know about is a minimum estimate as we can only know about those babies that were found. There were probably other unwanted babies over this time whose deaths were successfully concealed.
We feel this study is robust because it is based on a very large geographically defined population of 828 648 live births. The PMS has always had very high ascertainment, in some years in excess of the figures known to the Office of National Statistics. We suspect that other authors (table 2) have studied ENSUD primarily because they have observed a cluster of deaths, and thereby have derived an inflated figure for the true incidence, as we would have done had we limited our study to the first 5 years (table 1) which had a fourfold higher incidence than the second quinquennium. We have avoided this problem by collating events over a much longer period of time, and we have not been motivated by observing only those events that occurred in close temporal association. We recognise that our definition was both more restricted (excluding deaths fully explained clinically or on autopsy), and broader (including babies ≥ 34 weeks) than other authors, but neither of these definitional issues can explain the much lower rate, in comparison to other studies, that we report.
A limitation was that the clinical information available to us was inevitably incomplete. Ideally, we would have liked to look at other factors such as maternal obesity, smoking, family history of previous infant deaths, sleeping arrangements and other relevant details to gain a better understanding of the factors leading to death. A further limitation is that autopsies were not done on two infants. For these, we relied on indirect information so we have some risk of mis-categorising these infants. A baby who collapsed in the first week, but only went on to die as a result of that collapse after the end of the first week, will not have been included in this study; however for the purposes of making a robust calculation of incidence the age at death has to be the criterion. Finally, we only know about those babies who died: babies who nearly died, though very informative, are much more difficult to ascertain. It is to be hoped that the recent British Paediatric Surveillance Unit survey of early infant collapse will fill this gap.
The fact that primiparous mothers were over-represented among women whose babies died at the breast, and that in hospital the deaths clustered in the evening and night-time, suggests that both maternal inexperience and reduced professional supervision and support may have been factors in a proportion of the deaths. Others5 6 have observed that some infants are found collapsed or dead at the breast while in skin-to-skin contact with their primiparous mothers and suggested that acute respiratory obstruction may have caused the death. Foran reported severe neuronal damage in six infants who suffered postnatal collapse on their mothers' breast and suggested that unrecognised asphyxia might have resulted in brainstem or basal ganglia damage which could have impaired coordination of breathing and swallowing.7 Some authors have advocated enhanced supervision of new first-time mothers to avoid deaths at the breast, but there are obvious practical limitations to this, as our data suggest that across the north of England around 25 000 breast feeding women would have to receive such extra intrusive supervision, mostly at night, to possibly prevent one death.
We conclude both that unexplained ENSUD is far more rare than has been appreciated, and that there is no suggestion that changes in practice over the last 25 years have been associated with an increasing incidence. When such deaths occur, detailed postmortem investigations must be undertaken to try to ascertain the cause, since in some cases there may be implications for future pregnancies, and all families deserve to have an explanation of these particularly distressing deaths if that is possible.
The authors are indebted to Mary Bythell, RMSO Coordinator and Dr Chris Wright, Consultant Paediatric Pathologist, for their assistance with this work.
Competing interests None.
Ethics approval The perinatal mortality survey database was set up with ethics consent from the Ethics Committee of the Northern Regional Health Authority.
Provenance and peer review Not commissioned; externally peer reviewed.
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