Epidemiology of sudden infant death syndrome in Japan

An epidemiological survey was carried out to examine the present situation with respect to sudden infant death syndrome (SIDS) in Kanagawa Prefecture. Questionnaires on sudden unexpected death of infants aged < 1 year in 1990-91 were sent to the hospitals and clinics in Kanagawa Prefecture which may take care of such infants. By analysing information from 10 485 replies, 48 out of 73 reported sudden infant deaths were confirmed to be SIDS, although autopsy was not performed in 13 cases (27%). The incidence of SIDS per 1000 live births in Kanagawa Prefecture was 0.29 in 1990 and 0.31 in 1991; and if limited to autopsy cases 0.19 and 0.25, respectively. Sudden infant death syndrome cases in Japan were found to occur more frequently when infants were < 6 months old, at home and sleeping alone, but less in the winter and between midnight and early morning. There was little difference between the numbers in prone and supine sleeping positions at discovery. It was not clear whether SIDS occurred more often to babies sleeping prone than supine, because there were no controls matched with the SIDS cases. In future, continuous epidemiological surveys of SIDS in Japan should be carried out.     

Transepidermal water loss during sleep in infants at risk for sudden death

To search for excessive sweating during sleep in infants considered at risk for sudden infant death syndrome (SIDS), we studied 258 infants during one night. There were 134 normal infants (controls), 85 siblings of SIDS victims (siblings), and 39 infants who survived an apparent life-threatening event (ALTE) with no cause found for the incident. Mean postnatal ages were between 10 and 16 weeks. Transepidermal water evaporation rate was measured from the forehead using an evaporimeter during one night's polygraphic sleep recording. Measurements were made before feedings, during the first part of the night, and evaporation rate values were expressed as grams per square meter of body surface area per hour. In the three groups of patients evaporation rates were significantly lower during rapid eye movement (REM) sleep, compared with values measured during quiet wakefulness or nonrapid eye movement (NREM) sleep. Infants with an ALTE had significantly higher evaporation rate values during NREM sleep than the two other groups (20.1 +/- 1.93, 11.3 +/- 0.68, and 11.5 +/- 0.98 for the ALTE, control, and sibling infants, respectively). The differences were not related to age, sex, weight, or rectal temperature. During NREM sleep, evaporation rate values greater than 25 mg/m2/h were seen in 10/190 (5.3%) of the asymptomatic infants and in 11/36 (30.6%) of the infants with an ALTE. The results are in agreement with reports in the literature of repeated night sweating in infants who eventually died of SIDS. Although we are unable to conclude why evaporation rate values are higher in the ALTE group than in the two other groups, we cannot exclude that it reflects differences in autonomous system activity.(ABSTRACT TRUNCATED AT 250 WORDS)     

Responses to partial nasal obstruction in sleeping infants

Partial nasal obstruction was performed during a morning of quiet sleep (QS: non-REM) and active sleep (AS: REM) at ages 1 week, 2 weeks, 1, 2, 3, 4 and 6 months on 12 normal infants, 15 subsequent siblings of victims of the Sudden Infant Death Syndrome (SIDS) and 12 infants admitted for investigation of infant apnoea ('near-miss' SIDS). In all three groups the numbers failing to arouse after 240 s (FTA-240) in QS were significantly greater than those in AS. After 2 months of age all groups showed a decrease in the number FTA-240 in AS, whereas in QS the number did not change significantly. Subsequent siblings of SIDS had a significantly higher number FTA-240 in QS than controls. There was no significant difference in FTA-240 in QS between controls and infant apnoeas, although there was a trend for this to be higher in subsequent siblings of SIDS than infant apnoeas.
It was concluded that arousal from AS is more marked than from QS, that after 2 months of age the ability to arouse from AS increases, and that in relation to SIDS, QS is the sleep state in which the infant is less able to arouse. Furthermore, subsequent siblings of SIDS differ from normal infants in their ability to arouse from QS.     

Determinants of infant sleep position in an urban population

The incidence of SIDS has decreased by 40% since the Back to Sleep campaign was initiated. However, the rate of SIDS in the District of Columbia continues to be approximately double the national rate. The purpose of this study was to determine the prevalence and determinants of prone sleeping among infants in the District of Columbia and to ascertain what information is being provided to parents by health care professionals by a cross-sectional survey of parents of infants 0-6 months of age presenting for well child care at Children's Health Center, Children's National Medical Center, in Washington, DC. We recruited a consecutive sample of 126 parent-infant pairs, of which 92.9% were African-American. The average infant was 73 days old, was 3,003 grams at birth, and was full term. When asked how the infants were placed for sleep the night before the interview, 34.1 % of parents had placed the infant supine, 50.8% side, and 15.1% prone. Nearly half (48%) of infants slept in an adult bed with the mother. More than one third of the infants had been placed prone for sleep at least once since hospital discharge. Most common reasons for sleeping supine included SIDS risk reduction or health care professional advice. Side sleepers did so primarily because of concern about vomiting, health care provider advice, or SIDS. Infants were placed prone primarily because the infant slept better. When asked about information received from a health care provider, 70.6% of parents stated that they had received information about sleep position and 64.3% about the hazards of passive smoking. Eight parents observed nursery personnel placing their infants prone. Only 16.7% of the total study population had received a Back to Sleep brochure, read it, and recalled that it recommended back sleeping. Infants were more likely to sleep prone if there was a grandparent in the home (OR 2.9, p<0.05) or if they were the firstborn (OR 2.17, p<0.05). Infants were more likely to sleep supine if parents had heard a back recommendation from a health care professional (OR 5.7, p<0.001). Infants were least likely to sleep supine if the parents had heard a side or a side/back recommendation (OR 0.26, p=0.001). Infant sleep position was not ter, reading the Back to Sleep brochure. In conclusion, more than one third (35.7%) of infants in this predominantly African-American population have been placed prone for sleep at least once; 15% slept prone the night before the interview. Almost one third of parents received no information about sleep position, but parents receiving a verbal supine recommendation were most likely to place their infant supine. Receiving written information did not affect sleep position. Improved educational efforts for parents of African-American newborns should continue to focus on encouraging supine positioning, smoke cessation, and other safe sleep practices.     

SUDDEN INFANT DEATH IN COPENHAGEN 1956–1971

ABSTRACT. 131 cases of the Sudden Infant Death Syndrome (SIDS) among infants born in the Municipality of Copenhagen in 1956-71 were analysed on the basis of data collected prospectively by the infant health visitors. Compared with living controls, the frequency of maturity and the mean birth weight and length were lower among the SIDS infants. After making the SIDS and control groups comparable with respect to birth weight and type of feeding, we found a tendency towards a slower growth rate among the SIDS victims. The SIDS victims started to smile and prattle later than controls, while there was no difference as regards the average age at which the infants became able to hold their heads. It is concluded that the differencses are so small and the individual variations so wide that birth weight and length, growth rate, and psychomotor development will not be useful predictors of the SIDS.     

The healthy human infant tends to sleep in the prone rather than the supine position

There are few reports about developmental behavior relating to roll over among healthy infants. We assessed the relationship between the placed position on sleeping and altered sleeping position the next morning by roll over among healthy infants. A health check-up clinic distributed a total of 1626 questionnaires to parents whose infant's ages are 1.5 years (or 18 months) old. The age at the first roll over and the change in sleeping position the next morning after they started to roll over, were investigated. The mean age of roll over from the supine to the prone among infants who were placed mainly in the prone sleeping position, at least in the first week of life, was 4.0 months (S.D., 1.1). The mean age of roll over from the supine to the prone among infants who were placed mainly in the supine sleeping position during early neonatal life and thereafter was 4.4 months (S.D., 1.2). The age of the first roll over from supine to prone was significantly younger in infants who were placed mainly in the prone sleeping position during early neonatal life. Among 651 infants who had been placed supine, 34.7% were found prone by roll over the next morning. Among 211 infants who had been placed prone, 14.2% were found supine by roll over the next morning. The number of infants who rolled over from supine to prone position was statistically greater than those from prone to supine. It is likely that the healthy human infant tends to sleep in the prone rather than the supine position. The finding is especially important for the correct assessment of the position in which SIDS cases were found dead.     

Sudden infant death syndrome: How much mothers and health professionals know

Background: Behavioral risk factors are associated with sudden infant death syndrome (SIDS). Education about the risk factors of SIDS is important for prevention. Our aim was to determine the knowledge and attitude of parents and health professionals about SIDS. Methods: A total of 174 health professionals and 150 mothers were enrolled in this study. Mothers' data were collected by telephone interview and health‐care professionals were interviewed by the same investigator. Results: Only 39% of mothers were aware of SIDS. Forty‐six percent of the mothers preferred a supine sleeping position for their infant and 16% of the parents were bed‐sharing with their infants. Seventy‐three percent of health professionals selected side, 17% supine and 10% prone sleeping position as the safest sleeping position. Frequencies for awareness of risk factors were: bed‐sharing (75%), soft bedding (70%), pillow use (52%), toys in bed (90%), high room temperature (67%) and smoking (88%). Total knowledge score of health professionals who selected supine sleeping position as the safest was significantly higher (P < 0.001). Conclusion: Most of the mothers were unaware of SIDS and less than half preferred a supine sleeping position for their infant. Only 72% of health professionals recommended a certain sleeping position during family interviews. Health professionals are more often recommending the side sleeping position or prone. Education of families and health professionals for the risk factors of SIDS may reduce the number of deaths from SIDS in Istanbul.     

Sinus tachycardia in term infants preceding sudden infant death

The quantities of sinus tachycardia in 24-h recordings of the electrocardiogram from 16 full-term infants (37 weeks gestation) who were subsequently victims of the sudden infant death syndrome (SIDS), from 230 randomly selected age-matched full-term survivors and from 64 full-term survivors matched for age and birth weight were measured by computer and manual analysis techniques. Of 16 infants dying of SIDS, 7 had elevated levels of sinus tachycardia (>95th centile in controls) (P<0.01). Although high levels of sinus tachycardia might be of value in identifying infants at high risk of SIDS, these encouraging findings must first be validated by further prospective studies.Abbreviations IHR instantaneous heart rate - SIDS sudden infant death syndrome - ECG electrocardiogram     

Prone sleeping position increases the risk of SIDS in the day more than at night

BACKGROUND: SIDS mortality is higher during the night than in the day. AIM: (1) To examine risk factors for SIDS by time of day and (2) to see if the proportion of deaths at night has changed from prior to the 'Back to Sleep' campaign, which recommended infants sleep supine. METHODS: A large population-based SIDS matched case-control (GeSID) study conducted from 1998 to 2001 (when the prevalence of infants placed prone to sleep was 4.1%). The reference sleep of the controls was matched for the estimated time of death for the case. Risk factors for SIDS were examined for night-time and day-time deaths. The estimated time of death was compared with that from an earlier study in Germany (1990-1994 when prevalence of prone sleeping was 32.2%). RESULTS: There were 333 SIDS cases and 998 matched controls. The increased risk with placed prone to sleep was significantly different during the day [adjusted OR = 18.15 (95% CI = 5.91-55.69)] compared with during the night [adjusted OR = 3.49 (95% CI = 1.46-8.39; p-value for interaction = 0.011)]. There was no significant difference in the other risk factors examined by time of day in the multivariate analysis. The mean time found dead was 09:07. In the earlier study the mean time found dead was 08:54 and the difference was not significant (p = 0.57). CONCLUSIONS: This study confirms previous observations that prone sleeping position carries a greater risk during the day than at night. However, the reduction in infants sleeping prone has not been associated with a reduced number of deaths in the day in Germany.     

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.     

Pneumographic studies: Predictors of future apnoeas but not sudden infant death in asymptomatic infants

Abstract Pneumograms were performed on 401 asymptomatic infants: 322 siblings, 15 cousins and 24 twins of sudden infant death syndrome (SIDS) victims; 14 siblings of near-miss SIDS victims, and 26 infants of anxious parents. The infants of anxious parents had significantly fewer abnormalities than siblings of SIDS victims. In 222 infants subsequently monitored at home, the pneumogram as a predictor of future apnoea had a sensitivity rate of 97.5% and a specificity rate of 72% ( P < 0.001). Infants who were to experience future apnoeas had a significantly higher percentage of time in periodic breathing and a higher density of apnoeas in their original pneumograms. However, the abnormal pneumogram did not predict SIDS, because the eight infants who died all had normal pneumograms.     

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.     

Stop SIDS--sleeping solitary supine, sucking soother, stopping smoking substitutes

The recognition of prone sleeping and maternal smoking as modifiable risk factors for sudden infant death syndrome (SIDS), has drastically decreased SIDS incidence. However, during the last years other factors have become necessary to consider to further reduce the risk of SIDS. Side sleeping implies a greater risk than supine sleeping but is still common. Bed sharing may increase the risk of SIDS, while use of a pacifier seems to be protective. Replacement of maternal smoking with nicotine substitutes is not harmless.

Conclusion: To further reduce the risk of SIDS, exclusive supine sleeping should be encouraged and side sleeping discouraged. When the breast-feeding is established, a pacifier can very well be used at bedtime. Bed sharing can increase the risk of SIDS if the infant is below 2-3 months of age, especially if the mother is a smoker. Any nicotine use should be avoided during pregnancy and breast-feeding.     

Reduced arousals following obstructive apneas in infants sleeping prone

A decreased arousability and an increased risk for sudden infant death syndrome (SIDS) have been shown in infants sleeping prone. Obstructive apnea, a known risk factor for SIDS, is less often terminated by an arousal reaction in infants than in adults. The effect of body position on the arousal reaction to spontaneous respiratory events had not been previously studied in infants. The aim of our study was to see if body position has an influence on the frequency and delay of the arousal reaction to obstructive apnea. All obstructive events recorded during two successive nights in 20 infants sleeping one night prone and one night supine were studied. During the supine recording 153 obstructive events were detected, and 217 were detected during the prone session. Prone sleep was not associated with an increased frequency of obstructive apneas. Total sleep time was 382 min (range, 283-456) supine and 423 min (range, 325-521) prone (p = 0.003). Obstructive events duration was 6.5 s (range, 3-21.5) when sleeping supine and 8 s (range, 3.5-30.5) when prone (p = 0.002). Behavioral arousal were found in 57.5 % of obstructive events recorded supine and in 31.3 % of those seen prone (p < 0.001). Arousal occurred after 8 s (range, 0-21) from the start of the obstructions when supine and 10.5 s (range, 3.5-23.5) when prone (p = 0.001). Sighs were found in 34 % of supine obstructive events and in 44.7 % of those prone (p = 0.040). A reaction, i.e. arousal or sigh, was found in 91.5 % of supine events and 76 % of those prone (p < 0.001). We conclude that when sleeping supine, infants arouse to obstructive events more often and after shorter delay than when prone.     

Sudden Infant Death in Stockholm

ABSTRACT. During a ten year period, March 1976-February 1986, 83 non-selected consecutive cases of sudden unexpected death in infants, between one week and one year of age, were examined at the Department of Forensic Medicine in Stockholm. Forty-three deaths (52%) were classified as typical or possible cases of Sudden Infant Death Syndrome (SIDS), 35 (42%) as non-violent non-SIDS cases and 5 (6%) as non-natural deaths. Cardiovascular disease, including myocarditis, was found in 21 (25%) instances, infections with inflammatory manifestations in various organs outside the heart in 12 (14%) and miscellaneous, non-violent causes of death in 2 (2%) cases. The male: female ratio was 1.15:1 for SIDS and 1.30:1 for non-SIDS cases. A peak of incidence was found for SIDS cases in infants between two and four months of age, while non-SIDS victims tended to be somewhat older. Ninety-five percent of the SIDS fatalities occurred during the winter months (October-April) as compared to 71% of the non-SIDS cases. Outdoor temperature below the annual mean of 5.9°C in combination with a sudden decrease in temperature was associated with sudden deaths, particularly SIDS. Thirty-three percent of the SIDS victims died in their cribs compared to 51% of the non-SIDS cases. Corresponding figures for deaths outdoors in a pram were 33% and 11%, respectively. Fourteen percent of the infants in both groups died while in bed with one of the parents. Ninety-five percent of the SIDS victims were previously healthy, but in 9% one or more periods of abnormal breathing had been noted. The corresponding figures for non-SIDS were 70% and 3%, respectively. Among the cases of non-natural deaths was one infant who died of heroin poisoning and one of hypothermia.     

Early neonatal sudden death or near death syndrome. An epidemiological study of 29 cases

Early neonatal sudden death syndrome (SIDS) is a rare but well known disease entity. Between January 1975 and December 1991, 29 full-term newborn infants delivered in our maternity unit and, considered healthy at birth, suffered early SIDS ( n = 15) or early apparent life threatening events (ALTE) ( n = 14). Data from the whole population of live full-term infants born in our hospital during the past five years have been used as a reference (n = 27 841). The general rate of early SIDS was 0.14 per 1000 (15/107 263). Combining early ALTE cases, the overall rate was 0.27 per 1000 (291107263). A postmortem examination was performed for all infants who died (20/29): no cause of death could be determined, and we did not observe a single case with evident sequelae. There were 9 deaths (31 %) within the first hour after delivery and 12 deaths occurred in the early morning hours (04:00–08:00; RR = 3.76; p = 0.0008). The lowest incidence was in the spring (RR = 0.21; p = 0.03). There was a tendency for an increased incidence during the weekend and the summer. No influence of sex, maternal age, gestational age, infant weight presentation, delivery, anesthesia or presence of meconium-stained fluid was found. In our opinion, SIDS can take place even during the first hour of life and it is not possible to predict when a baby might be affected. Pediatrically trained caregivers, close observation by the mother during the first few days and resuscitation facilities in maternity wards may be the most important preventive measures to reduce the risk of early SIDS and the consequences of ALTE in the early newborn period.     

Child care practices and the sudden infant death syndrome

Abstract Southern New Zealand has one of the highest reported rates of the sudden infant death syndrome (SIDS) in the world. Data were collected on 49 infants who died from SIDS in the Dunedin and Invercargill Health Districts of southern New Zealand. Forty-two of the families were interviewed at home following the loss of their infant. In the week prior to death, 17 infants (40%) had an upper respiratory tract infection, although in 11 of these infants their infection had apparently resolved at least 24 h prior to death. Thirty infants (71%) had their faces down into the bedding or their heads covered with bedding. Thirty-four infants (81%) were found dead in the prone position, whereas 49% of New Zealand infants aged 3 months would be expected to sleep prone. Sleep position and the terminal position of the head in relation to SIDS requires further study.     

Nicotine and cotinine levels in pericardial fluid in victims of SIDS

Milerad J, Rajs J, Gidlund E. Nicotine and cotinine levels in pericardial fluid in victims of SIDS. Acta Paediatr 1994;83:59–62. Stockholm. ISSN 0803–5253
We have analyzed the levels of nicotine and cotinine in pericardial fluid in 24 consecutively autopsied cases of sudden unexpected death in infants aged one to six months. Our aim was to determine to what extent victims of sudden infant death may have been exposed to passive smoking near the time of death. Sixteen of the decreased infants were classified as SIDS at autopsy. Other contributing causes of death, predominantly infections, were found in eight cases. Eight infants (30%) had cotinine levels less than 2 ng, indicating that no significant exposure to nicotine had occurred near the time of death. Of the remaining 70%, five had been moderately exposed, seven markedly exposed and four heavily exposed (cotinine levels 2–10 ng, 10–50 ng and more than 50 ng, respectively). Since only 18% of Swedish women smoke after childbearing we conclude that nicotine exposure in infants who died suddenly was much higher than one would otherwise expect. It is hypothesized that high concentrations of nicotine and nicotine metabolites around the heart may affect cardiac function and thus play a role in the mechanisms causing SIDS or other categories of sudden unexpected death.     

Ventilatory pattern following diphtheria-tetanus-pertussis immunization in infants at risk for sudden infant death syndrome

To evaluate the effects of diphtheria-tetanus-pertussis (DTP) immunization on the ventilatory pattern during sleep in infants at increased risk for sudden infant death syndrome (SIDS), we performed overnight pneumograms (recordings of ventilatory pattern and electrocardiogram) on 30 control infants, 46 infants with unexplained apnea, and 33 subsequent siblings of SIDS victims the night before and the night following a DTP immunization. Pneumograms were quantitated for total sleep time, longest apnea (in seconds), total duration of apneas longer than 6 s (in minutes), and total periodic breathing (in minutes). Following the DTP immunization there was no significant change in any criterion quantitated on pneumograms from any group except for a decrease in periodic breathing in the unexplained apnea group. We conclude that DTP immunization does not increase abnormalities of the ventilatory pattern as recorded by the pneumogram technique in infants at increased risk for SIDS.