Recurrence of unexpected infant death

Families which had experienced two or more unexpected infant deaths were the subject of detailed confidential enquiries, including necropsy examination. Cases were derived from two main sources: first, deaths occurring during a nationwide programme of support for families with a subsequent baby (8 families) plus 2 families from a scries of confidential enquiries in Sheffield, and second, direct referrals from paediatricians (17 families). Fifty-seven deaths were studied. Twenty-four families had experienced 2 and three had experienced 3 deaths: 11 deaths (19%) were found to be adequately explained by history or post-mortem findings; 7 (12%) were probably accidental; 31 (55%) were most probably due to an action by one of the parents (filicide); only 5 (9%) were considered to be true or idiopathic sudden infant death syndrome; in 3 (5%) cases there was insufficient information to draw a conclusion. Five (18%) of the families lived in circumstances of serious social deprivation. A history of psychiatric illness was present in one or both parents in 18 (67%) of the families.     

Recurrence of unexpected infant death

Families which had experienced two or more unexpected infant deaths were the subject of detailed confidential enquiries, including necropsy examination. Cases were derived from two main sources: first, deaths occurring during a nationwide programme of support for families with a subsequent baby (8 families) plus 2 families from a scries of confidential enquiries in Sheffield, and second, direct referrals from paediatricians (17 families). Fifty-seven deaths were studied. Twenty-four families had experienced 2 and three had experienced 3 deaths: 11 deaths (19%) were found to be adequately explained by history or post-mortem findings; 7 (12%) were probably accidental; 31 (55%) were most probably due to an action by one of the parents (filicide); only 5 (9%) were considered to be true or idiopathic sudden infant death syndrome; in 3 (5%) cases there was insufficient information to draw a conclusion. Five (18%) of the families lived in circumstances of serious social deprivation. A history of psychiatric illness was present in one or both parents in 18 (67%) of the families.     

Overview of sudden infant death syndrome in Japan

In spite of rapid medical advancement in the care of infants and children, not only the general public but also many medical personnel have remained unaware of sudden infant death syndrome (SIDS) until very recently in Japan. In 1981, a research project team on SIDS financed by the Ministry of Health and Welfare was founded. Current incidence of SIDS is estimated to be about 0.5 per 1000 live births. The SIDS Family Association was organized in 1993 in Japan and began to publicize the social importance of SIDS and to support SIDS families by training befrienders. A series of articles on current achievements from SIDS research projects and from the SIDS Family Association are submitted to this issue. The present paper summarizes the status of SIDS in Japan by overviewing the activities of the research team and the SIDS Family Association.     

Formative evaluation to improve prevention of sudden infant death syndrome (SIDS): a prospective study

Aim: To evaluate formative evaluation, a pedagogic method that sensitizes mothers to sudden infant death syndrome (SIDS), as a new way to improve prevention of SIDS. Methods: Prospective and randomized study. Mothers in a test group (n = 148) received an educative questionnaire about SIDS during maternity stay. Three months later, we evaluated, by a telephonic interview, their scores of knowledge and observance of the recommendations in comparison with a control group (n = 144). Results: Mothers’ scores at the educative questionnaire was 5.12 (1.52) [mean(standard deviation)]. The scores performed 3 months later were better in test group for knowledge [7.64 (1.56) vs. 7.16 (1.61), p < 0.01] and for observance [8.28 (1.51) vs. 7.62 (1.72), p < 0.001]. Logistic regression analysis confirmed the benefits in test group regarding knowledge of SIDS risk factors [ORa = 1.69 (1.02–2.77), p < 0.05], of the advice to avoid overheating infants [ORa = 2.50 (1.43–4.38), p < 0.01] and of the risks of bed sharing [ORa = 2.7 (1.6–4.5), p < 0.001]. There was a significant association between non‐compliance with the sleeping position recommendation and unemployment (p < 0.01) and absence of postsecondary school education (p < 0.01). Conclusion: Formative evaluation using an educative questionnaire could improve maternal awareness on SIDS risk factors and their compliance with recommendations about SIDS prevention.     

Analysis of the mitochondrial genome in sudden infant death syndrome

AIM: To investigate the mitochondrial genome and its association with sudden infant death syndrome (SIDS). METHODS: Twenty SIDS infants were screened for previously reported mitochondrial DNA mutations using direct sequencing. The whole mitochondrial genome was also sequenced for six of the infants. RESULTS: Three substitutions, A11467G, A12308G and G12372A, comprising a haplogroup were present in four infants diagnosed as pure SIDS. This haplogroup was also common in a control group. CONCLUSIONS: No specific mutation or polymorphism was found in association with SIDS.     

The airway occlusion test as a screening for sudden infant death syndrome (SIDS)

The airway occlusion test was carried out as a screening test for sudden infant death syndrome (SIDS). To obtain the normal values for use as control values, the relationship of the airway occlusion test with various variables was determined in 234 infants. The result shows that the best correlation was seen between percentage prolongation and the corrected gestational age. Percentage prolongation increased with the progression of age up to about the 40th week of corrected gestational age. Subsequently, there was no remarkable change in percentage prolongation. In six out of eight cases with apparent life threatening events, percentage prolongation was reduced. These results indicate that the determination of percentage prolongation can be used for screening of high risk babies for SIDS.     

Impact of home monitoring for sudden infant death syndrome on family life

As home monitoring has been advocated for the prevention of sudden infant death (SIDS) we investigated the influence of such a monitoring programme on family life. Twenty European middle and lower-class families with a child monitored at home after a near miss for SIDS event were investigated. Some psychological and social findings were compared with a group of 20 matched control families. It appears that home monitoring induces severe stress, mainly in the mothers. Fathers and siblings also manifested significant emotional stress. Poor schooling of the parents and previous marital discord seem to be predictors of bad adaptation to home monitoring.     

A case-control study of smoking and sudden infant death syndrome in the Scandinavian countries, 1992 to 1995. The Nordic Epidemiological SIDS Study

AIM: To establish whether smoking is an independent risk factor for sudden infant death syndrome (SIDS), if the effect is mainly due to prenatal or postnatal smoking, and the effect of smoking cessation. METHODS: The analyses were based on data from the Nordic epidemiological SIDS study, a case-control study with 244 cases and 869 controls. Odds ratios were computed by conditional logistic regression analysis. RESULTS: Smoking emerged as an independent risk factor for SIDS, and the effect was mainly mediated through maternal smoking in pregnancy (crude odds ratio 4.0 (95% confidence interval 2.9 to 5.6)). Maternal smoking showed a marked dose-response relation. There was no effect of paternal smoking if the mother did not smoke. Stopping or even reducing smoking was beneficial. SIDS cases exposed to tobacco smoke were breast fed for a shorter time than non-exposed cases, and feeding difficulties were also more common. CONCLUSIONS: Smoking is an independent risk factor for SIDS and is mainly mediated through maternal smoking during pregnancy. Stopping smoking or smoking less may be beneficial in reducing the risk of SIDS.     

Sleeping position and sudden infant death syndrome (SIDS): effect of an intervention programme to avoid prone sleeping

The proportion of prone sleeping among sudden infant death syndrome (SIDS) victims and infants in general, and the rate of SIDS were prospectively studied in the county of Hordaland, Norway, three years before (1987–89) and three years after (1990–92) a campaign to discourage prone sleeping. Before the campaign, 64% of random reference infants were put prone versus 8% after (p < 0.0001). Concurrently, the rate of SIDS decreased from 3.5 to 1.6 per 1000 live births (63 infants before and 30 after the campaign, p = 0.0002). Prone sleeping was not considered a statistically significant risk factor for SIDS before (OR 2.0,95% CI 0.8–4.5), but was highly significant (OR 11.3,95% CI 3.6–36.5) after the campaign. Prone sleeping is an important risk factor for SIDS, but the association may be missed in epidemiological studies if prone is the predominant sleeping position. Behaviour with regard to sleeping position may be changed rapidly by means of a simple campaign.     

Caffeine and alcohol as risk factors for sudden infant death syndrome. Nordic Epidemiological SIDS Study.

OBJECTIVE: To assess whether alcohol and caffeine are independent risk factors for sudden infant death syndrome (SIDS). MATERIALS AND METHODS: Analyses based on data from the Nordic epidemiological SIDS study, a case control study in which all parents of SIDS victims in the Nordic countries from 1 September 1992 to 31 August 1995 were invited to participate with parents of four controls, matched for sex and age at death. Odds ratios (ORs) were calculated by conditional logistic regression analysis. RESULTS: The crude ORs for caffeine consumption > 800 mg/24 hours both during and after pregnancy were significantly raised: 3.9 (95% confidence interval (CI), 1.9 to 8.1) and 3.1 (95% CI, 1.5 to 6.3), respectively. However, after adjustment for maternal smoking in 1st trimester, maternal age, education and parity, no significant effect of caffeine during or after pregnancy remained. For maternal or paternal alcohol use, no significant risk increase was found after adjusting for social variables, except for heavy postnatal intake of alcohol by the mother, where the risk was significantly increased. CONCLUSIONS: Caffeine during or after pregnancy was not found to be an independent risk factor for SIDS after adjustment for maternal age, education, parity, and smoking during pregnancy. Heavy postnatal but not prenatal intake of alcohol by the mother increased the risk.     

Problems on the diagnosis of sudden infant death syndrome

Various autopsy cases of sudden unexpected death (SUD) in infancy were examined at the Tokyo Medical Examiner's Office between 1985 and 1994. More than half of the SUD were diagnosed as sudden infant death syndrome (SIDS), but a number of other causes, such as mechanical asphyxia, were also diagnosed. SIDS is diagnosed by autopsy, but there are no clear diagnostic criteria differentiating SIDS from other causes of SUD. SUD is diagnosed as SIDS when other causes are excluded, but it is difficult to distinguish between SIDS and mechanical asphyxia. There was not a large difference in autopsy findings, or in death scene or statistical data, between SIDS and non-SIDS cases. In their estimation of the diagnostic ratio of SIDS to other causes of death, medical examiners might be divided into three groups: ‘SIDS tolerationist’ examiners think that SUD should be positively diagnosed as SIDS, insofar as another cause of death is not proved clearly. A second group of examiners might be regarded as ‘SIDS exclusionist’; these consider microscopic findings or peculiar death scenes as important contributing factors leading to death. The third group represents a middle stance somewhere between these two. We thought that (forensic) pathologists as well as medical examiners in Japan might have differing stances on SIDS diagnosis. The statistical analysis of SIDS in certain research areas may be affected by the diagnostic ‘preference’ of pathologists belonging to a certain institute.     

Study of the conduction system in a population of patients with sudden infant death syndrome

Summary The conduction system of 23 infant hearts, 15 of sudden infant death syndrome (SIDS) and eight of those dying from known cause, was serially sectioned. A left-sided His bundle was found more commonly in (SIDS) (eight of 15) than in the controls (two of eight). Taking into account a previous study in which a left-sided His bundle was found in only four of 32 hearts from all age groups, this is statistically significant and may be a factor promoting SIDS.This research was aided by grant HL-30558-02 from the National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland.     

Serum testosterone and estradiol in sudden infant death

OBJECTIVE: To test the hypothesis that among infants who die unexpectedly, testosterone and/or estradiol levels are elevated in those diagnosed with SIDS versus those with known causes of death (controls). STUDY DESIGN: Postmortem blood was collected and coded from infant autopsies, and serum was prepared and frozen until assayed for total testosterone and estradiol by fluoroimmunoassay. Subject information was then collected from the medical examiner's report. RESULTS: Testosterone, but not estradiol, was significantly higher in 127 SIDS cases versus 42 controls for both males (4.8 +/- 0.4 vs 2.2 +/- 0.4 nmol, respectively; P < .005) and females (2.4 +/- 0.2 vs 1.6 +/- 0.2 nmol, respectively; P < 0.03). CONCLUSIONS: Higher testosterone levels in infant victims of unexpected, unexplained death may indicate a role for testosterone or related steroids in SIDS. Further research is needed to understand the potential utility of testosterone as an indicator of SIDS risk.     

Mitochondrial tRNA genes and flanking regions in sudden infant death syndrome

AIM: Mitochondrial DNA (mtDNA) mutations have been proposed as a genetic risk factor for sudden infant death syndrome (SIDS). The aim of this study was to further investigate this issue, by sequencing the mitochondrial tRNA genes with flanking regions in SIDS cases and controls. METHOD: The selected genes were investigated in 24 cases of SIDS and 10 controls, the method used were direct sequencing. In addition, the A10398G mutation in the ND3 gene was investigated in 220 SIDS cases, 26 cases of infectious death and 93 controls, using allele-specific PCR. RESULTS: Mutations, recorded as differences from the revised Cambridge sequence, were found in 32 different sites in the coding regions investigated. There was no difference in mutation frequency between SIDS cases and controls, and no single mutation was found associated with SIDS. CONCLUSION: The present study does not indicate an association between a specific mitochondrial tRNA gene mutation and SIDS, nor a higher mtDNA tRNA mutation frequency in SIDS cases than in controls.     

A screening program for detecting children with an increased SIDS risk (sudden and unexpected infant death)

The prospective study presented conducted to prevent SIDS (sudden infant death syndrome). One of the proposed hypotheses on SIDS postulates a brainstem abnormality in the neuroregulation of cardiorespiratory processes. Therefore we characterized cardiorespiratory control mechanisms by examining the neurotransmitter substance P in plasma and polysomnographic investigations. With respect to the probable multifactorial origin of SIDS we selected children firstly anamnestically by means of an epidemiologically evaluated pre-, peri- and postnatal risk score. We reported the results of 208 polysomnographically and biochemically examined children anamnestically selected from a group of 2500 neonates. Examinations were performed on infants aged 2-4 weeks up to 1 year. To characterize respiratory control, length and frequency of apnoeas were separately estimated by means of polysomnography in the sleep states active and quiet sleep. If there were polygraphic risk factors representing a disturbance of respiratory control, the children were prophylactically treated with aminophylline 3 x 3 mg/kg b.w. for 4 weeks. We found a significant age dependence both of the mean apnoea duration in active sleep and the substance P level in plasma in the SIDS-risk group but not in the controls. High mean apnoea duration was correlated with low substance P level in the first months of age in SIDS risk infants selected anamnestically. This may reflect a delayed maturation of respiratory control mechanisms. In this way the polysomnography and the investigation of the neuropeptide substance P may be useful for a screening method indicating wether the respiratory control mechanisms are mature or not.     

Prevention of sudden infant death syndrome (SIDS) due to an active health monitoring system 20 years prior to the public "Back to Sleep" campaigns

Background

Before reunification, the post‐neonatal mortality rate was lower in East Germany than in West Germany. Moreover, the incidence of SIDS (sudden infant death syndrome) was much lower in the East.

Methods

Mortality data on sudden infant death syndrome (SIDS) from West and East Germany since 1980 as well as post‐neonatal mortality data for both states since 1970 were examined. 95% Confidence intervals were calculated for the rates. Witnesses from the former East Germany who were involved at the time were also interviewed and archives were searched.

Results

We found that as early as 1972 active monitoring of infant and child mortality rates in East Germany had shown that the prone sleeping position was dangerous for infants: the post‐neonatal mortality rate was approximately 1 per 1000 live births lower in East than in West Germany during the 20 years before reunification. In contrast, in the West, prone sleeping was only discovered to be a risk factor for SIDS in the early 1990s.

Conclusions

Active monitoring is an effective tool in the early detection of risk factors and serves to prevent unnecessary deaths.