Population trends in sudden infant death syndrome

The global burden of sudden infant death syndrome from 1990 to 2019: a systematic analysis from the Global Burden of Disease study 2019

BACKGROUND

Sudden infant death syndrome (SIDS) still remains one of the leading causes of infant death worldwide, especially in high-income countries. To date, however, there is no detailed information on the global health burden of SIDS.

AIMS

To characterize the global disease burden of SIDS and its trends from 1990 to 2019 and to compare the burden of SIDS according to the socio-demographic index (SDI).

DESIGN

Systematic analysis based on the Global Burden of Disease (GBD) 2019 data.

METHODS

Epidemiological data of 204 countries from 1990 to 2019 were collected via various methods including civil registration and vital statistics in the original GBD study. Estimates for mortality and disease burden of SIDS were modeled. Crude mortality and mortality rates per 100 000 population were analyzed. Disability-adjusted life years (DALYs) and DALY rates were also assessed.

RESULTS

In 2019, mortality rate of SIDS accounted for 20.98 [95% Uncertainty Interval, 9.15-46.16] globally, which was a 51% decrease from 1990. SIDS was most prevalent in Western sub-Saharan Africa, High-income North America and Oceania in 2019. The burden of SIDS was higher in males than females consistently from 1990 to 2019. Higher SDI and income level was associated with lower burden of SIDS; furthermore, countries with higher SDI and income had greater decreases in SIDS burden from 1990 to 2019.

CONCLUSIONS

The burden of SIDS has decreased drastically from 1990 to 2019. However, the improvements have occurred disproportionately between regions and SDI levels. Focused preventive efforts in under-resourced populations are needed.

Infant rolling abilities--the same or different 20 years after the back to sleep campaign?

AIM

To compare the order and age of emergence of rolling prone to supine and supine to prone before the introduction of back to sleep guidelines and 20 years after their introduction.

METHODS

The original normative data for the Alberta Infant Motor Scale (AIMS) were collected just prior to the introduction of back to sleep guidelines in 1992. Currently these norms are being re-evaluated. Data of rolling patterns of infants 36 weeks of age or younger from the original sample (n=1114) and the contemporary sample (n=351) were evaluated to compare the sequence of appearance of prone to supine and supine to prone rolls (proportion of infants passing each roll) and the ages of emergence (estimated age when 50% of infants passed each roll).

RESULTS

The sequence of emergence and estimated age of appearance of both rolling directions were similar between the two time periods.

CONCLUSION

The introduction of the supine sleep position to reduce the prevalence of Sudden Infant Death Syndrome (SIDS) has not altered the timing or sequence of infant rolling abilities. This information is valuable to health care providers involved in the surveillance of infants' development. Original normative age estimates for these two motor abilities are still appropriate.

Timing, sleep, and respiration in health and disease

Breathing is perhaps the physiological function that is most vital to human survival. Without breathing and adequate oxygenation of tissues, life ceases. As would be expected for such a vital function, breathing occurs automatically, without the requirement of conscious input. Breathing is subject to regulation by a variety of factors including circadian rhythms and vigilance state. Given the need for breathing to occur continuously with little tolerance for interruption, it is not surprising that breathing is subject to both circadian phase-dependent and vigilance-state-dependent regulation. Similarly, the information regarding respiratory state, including blood-gas concentrations, can affect circadian timing and sleep-wake state. The exact nature of the interactions between breathing, circadian phase, and vigilance state can vary depending upon the species studied and the methodologies employed. These interactions between breathing, circadian phase, and vigilance state may have important implications for a variety of human diseases, including sleep apnea, asthma, sudden unexpected death in epilepsy, and sudden infant death syndrome.

Decisions of black parents about infant bedding and sleep surfaces: a qualitative study

OBJECTIVE

The goal of this qualitative study was to examine factors influencing decisions by black parents regarding use of soft bedding and sleep surfaces for their infants.

METHODS

We conducted focus groups and individual interviews with black mothers of lower and higher socioeconomic status (SES). Mothers were asked about many infant care practices, including sleep surface and bedding.

RESULTS

Eighty-three mothers were interviewed, 73 (47 lower and 26 higher SES) in focus groups and 10 (7 lower and 3 higher SES) in individual interviews. The primary reason for using soft surfaces was infant comfort. Parents perceived that infants were uncomfortable if the surface was not soft. Many parents also interpreted "firm sleep surface" to mean taut; they were comfortable with and believed that they were following recommendations for a firm sleep surface when they placed pillows/blankets on the mattress as long as a sheet was pulled tautly over the pillows/blankets. The primary reasons for using soft bedding (including bumper pads) were comfort, safety, and aesthetics. In addition to using bedding to soften sleep surfaces, bedding was used to prevent infant rollover and falls, particularly for infants sleeping on a bed or sofa. Some parents used soft bedding to create an attractive space for the infant.

CONCLUSIONS

Many black parents believe that soft bedding will keep their infant safe and comfortable. There is much misunderstanding about the meaning of a "firm" sleep surface. Additional educational messages apparently are needed to change parental perceptions and practices.

Racial and ethnic disparities in infant mortality

Racial and ethnic disparities in infant mortality in the United States seem to defy all attempts at elimination. Despite national priorities to eliminate these disparities, black infants are 2.5 times more likely to die in infancy compared with non-Hispanic white infants. This disparity is largely related to the greater incidence among black infants of prematurity and low birth weight, congenital malformations, sudden infant death syndrome, and unintentional injuries. This greater incidence, in turn, is related to a complex interaction of behavioral, social, political, genetic, medical, and health care access factors. Thus, to influence the persistent racial disparity in infant mortality, a highly integrated approach is needed, with interventions adapted along a continuum from childhood through the periods of young adulthood, pregnancy, postpartum and beyond. The content and methodologies of these interventions need to be adapted to the underlying behaviors, social influences, and technology and access issues they are meant to address.

Postnatal parental smoking: an important risk factor for SIDS

BACKGROUND

Sudden infant death syndrome (SIDS) is the unexpected death of an infant that remains unexplained after a thorough investigation of the circumstances, family history, paediatric investigation and complete autopsy. In Western society, it is the leading cause of post-neonatal death below 1 year of age. In the Netherlands, the SIDS incidence is very low, which offers opportunities to assess the importance of old and new environmental risk factors. For this purpose, cases were collected through pathology departments and the working group on SIDS of the Dutch Paediatrician Foundation. A total of 142 cases were included; these occurred after the parental education on sleeping position (1987), restricted to the international age criteria and had no histological explanation. Age-matched healthy controls (N = 2,841) came from a survey of the Netherlands Paediatric Surveillance Unit, completed between November 2002 and April 2003. A multivariate analysis was performed to determine the risk factors for SIDS, including sleeping position, antenatal maternal smoking, postnatal parental smoking, premature birth, gender, lack of breastfeeding and socio-economic status. Postnatal smoking was identified as an important environmental risk factor for SIDS (OR one parent = 2.5 [1.2, 5.0]; both parents = 5.77 [2.2, 15.5]; maternal = 2.7 [1.0, 6.4]; paternal = 2.4 [1.3, 4.5] ) as was prone sleeping (OR put prone to sleep = 21.5 [10.6, 43.5]; turned prone during sleep = 100 [46, 219]). Premature birth was also significantly associated with SIDS (OR = 2.4 [1.2, 4.8]).

CONCLUSION

Postnatal parental smoking is currently a major environmental risk factor for SIDS in the Netherlands together with the long-established risk of prone sleeping.

Influence of swaddling experience on spontaneous arousal patterns and autonomic control in sleeping infants

OBJECTIVE

To investigate the effects of swaddling experience on infant sleep, spontaneous arousal patterns and autonomic control.

STUDY DESIGN

Twenty-seven healthy term infants, who were routinely swaddled at home (n=15) or "naïve" to swaddling (n=12), were monitored with daytime polysomnography in swaddled and unswaddled conditions at 3 to 4 weeks and at 3 months after birth.

RESULTS

Swaddling did not alter sleep time, spontaneous arousability, or heart rate variability in routinely swaddled infants at either age. During active sleep at 3 months, cortical arousal frequency was decreased, and total sleep time was increased by swaddling in infants who were naïve to swaddling. Heart rate variability when swaddled was also highest in the naïve group.

CONCLUSIONS

The effects of infant swaddling on sleep time, arousability, and autonomic control are influenced by previous swaddling experience. Infants in the naïve to swaddling group exhibited decreased spontaneous cortical arousal, similar to responses observed in future victims of sudden infant death syndrome. Infants in unfamiliar sleeping conditions may therefore be more susceptible to cardiorespiratory challenges that fail to stimulate arousal and may lead to sudden infant death syndrome.

Birth outcomes in the Inuit-inhabited areas of Canada

BACKGROUND

Information on health disparities between Aboriginal and non-Aboriginal populations is essential for developing public health programs aimed at reducing such disparities. The lack of data on disparities in birth outcomes between Inuit and non-Inuit populations in Canada prompted us to compare birth outcomes in Inuit-inhabited areas with those in the rest of the country and in other rural and northern areas of Canada.

METHODS

We conducted a cohort study of all births in Canada during 1990-2000 using linked vital data. We identified 13,642 births to residents of Inuit-inhabited areas and 4,054,489 births to residents of all other areas. The primary outcome measures were preterm birth, stillbirth and infant death.

RESULTS

Compared with the rest of Canada, Inuit-inhabited areas had substantially higher rates of preterm birth (risk ratio [RR] 1.45, 95% confidence interval [CI] 1.38-1.52), stillbirth (RR 1.68, 95% CI 1.38-2.04) and infant death (RR 3.61, 95% CI 3.17-4.12). The risk ratios and absolute differences in risk for these outcomes changed little over time. Excess mortality was observed for all major causes of infant death, including congenital anomalies (RR 1.64), immaturity-related conditions (RR 2.96), asphyxia (RR 2.43), sudden infant death syndrome (RR 7.15), infection (RR 8.32) and external causes (RR 7.30). Maternal characteristics accounted for only a small part of the risk disparities. Substantial risk ratios for preterm birth, stillbirth and infant death remained when the comparisons were restricted to other rural or northern areas of Canada.

INTERPRETATION

The Inuit-inhabited areas had much higher rates of preterm birth, stillbirth and infant death compared with the rest of Canada and with other rural and northern areas. There is an urgent need for more effective interventions to improve maternal and infant health in Inuit-inhabited areas.

The measurement of the QT and QTc on the neonatal and infant electrocardiogram: a comprehensive reliability assessment

BACKGROUND

An electrocardiogram has been proposed to screen for prolonged QT interval that may predispose infants to sudden death in the first year of life. Understanding the reliability of QT interval measurement will inform the design of a screening program.

METHODS

Three pediatric cardiologists measured the QT/RR intervals on 60 infant electrocardiograms (median age 46 days), from leads II, V5 and V6 on three separate occasions, 7 days apart, according to a standard protocol. The QTc was corrected by Bazett's (QTcB), Fridericia's (QT(CFrid)), and Hodges' (QTcH) formulae. Intraobserver and interobserver reliability were assessed by intraclass correlation coefficients (ICC), limits of agreement and repeatability coefficients for single, average of two and average of three measures. Agreement for QTc prolongation (> 440 msec) was assessed by kappa coefficients.

RESULTS

QT interval intraobserver ICC was 0.86 and repeatability coefficient was 25.9 msec; interobserver ICC increased from 0.88 for single observations to 0.94 for the average of 3 measurements and repeatability coefficients decreased from 22.5 to 16.7 msec. For QTcB, intraobserver ICC was 0.67, and repeatability was 39.6 msec. Best interobserver reliability for QTcB was for the average of three measurements (ICC 0.83, reproducibility coefficient 25.8 msec), with further improvement for QTcH (ICC 0.92, reproducibility coefficient 16.69 msec). Maximum interobserver kappa for prolonged QTc was 0.77. Misclassification around specific cut points occurs because of the repeatability coefficients.

CONCLUSIONS

Uncorrected QT measures are more reliable than QTcB and QT(CFrid). An average of three independent measures provides the most reliable QT and QTc measurements, with QTcH better than QTcB.

What is the mechanism of SIDS? Clues from epidemiology

The cause of sudden infant death syndrome (SIDS) is unknown. Many mechanisms have been postulated, although thermal stress, rebreathing of expired gases and infection/inflammation seem the most viable hypotheses for the causation of SIDS. Deaths from SIDS have reduced dramatically following the recommendation not to place infants to sleep prone. Epidemiological data have shown that prone sleeping position is more risky in winter, colder latitudes, higher altitudes, if the infant is unwell or has excessive bedding or clothing. This suggests prone sleeping position involves either directly or indirectly a thermal mechanism. SIDS caused by an infective/inflammatory mechanism might be associated with deaths occurring during the night. Rebreathing of expired gases, airway obstruction, long QT syndrome and other genetic conditions may explain a small number of sudden unexpected deaths in infancy.

Brainstem mechanisms underlying the sudden infant death syndrome: evidence from human pathologic studies

The brainstem hypothesis is one of the leading hypotheses concerning the sudden infant death syndrome (SIDS). It states that SIDS, or an important subset of SIDS, is due to abnormal brainstem mechanisms in the control of respiration, chemosensitivity, autonomic regulation, and/or arousal which impairs the infant's response to life-threatening, but often occurring, stressors during sleep (e.g., hypoxia, hypercarbia, asphyxia, hyperthermia) and leads to sudden death in a vulnerable developmental period. In this review, we summarize neuropathologic evidence from SIDS cases that support this hypothesis, beginning with the seminal report of subtle brainstem gliosis three decades ago. We focus upon recent neurochemical studies in our laboratory concerning the neurotransmitter serotonin (5-HT) and its key role in mediating protective responses to homeostatic stressors via medullary circuits. The possible fetal origin of brainstem defects in SIDS is reviewed, including evidence for adverse effects of prenatal exposure to maternal cigarette smoking and alcohol upon the postnatal development of human brainstem 5-HT pathways.

Sudden infant death syndrome and prone sleeping position

In this review, we describe the epidemiological work conducted by ourselves and others on prone sleep position and sudden infant death. What we have learned since 1990 is that the prone sleep position was a major component of a casual pathway that was operating in over half of the SIDS deaths that were occurring in developed countries at the end of the 1980. It has been estimated that advice to place infants supine to sleep may have saved in the order of 850 infants annually in Australia and other countries. The story of the SIDS epidemic is an example of the contribution that epidemiology can make to the understanding and prevention of an important public health problem.

Cardiac potassium channel dysfunction in sudden infant death syndrome

Life-threatening arrhythmias have been suspected as one cause of the sudden infant death syndrome (SIDS), and this hypothesis is supported by the observation that mutations in arrhythmia susceptibility genes occur in 5-10% of cases. However, the functional consequences of cardiac potassium channel gene mutations associated with SIDS and how these alleles might mechanistically predispose to sudden death are unknown. To address these questions, we studied four missense KCNH2 (encoding HERG) variants, one compound KCNH2 genotype, and a missense KCNQ1 mutation all previously identified in Norwegian SIDS cases. Three of the six variants exhibited functional impairments while three were biophysically similar to wild-type channels (KCNH2 variants V279M, R885C, and S1040G). When co-expressed with WT-HERG, R273Q and K897T/R954C generated currents resembling the rapid component of the cardiac delayed rectifier current (I(Kr)) but with significantly diminished amplitude. Action potential modeling demonstrated that this level of functional impairment was sufficient to evoke increased action potential duration and pause-dependent early afterdepolarizations. By contrast, KCNQ1-I274V causes a gain-of-function in I(Ks) characterized by increased current density, faster activation, and slower deactivation leading to accumulation of instantaneous current upon repeated stimulation. Action potential simulations using a Markov model of heterozygous I274V-I(Ks) incorporated into the Luo-Rudy (LRd) ventricular cell model demonstrated marked rate-dependent shortening of action potential duration predicting a short QT phenotype. Our results indicate that certain potassium channel mutations associated with SIDS confer overt functional defects consistent with either LQTS or SQTS, and further emphasize the role of congenital arrhythmia susceptibility in this syndrome.

Recommendations for sudden infant death syndrome prevention: a discussion document

This article reviews the evidence for the current UK Department of Health recommendations for prevention of sudden infant death syndrome (SIDS) and suggests other factors that should be considered. The wording of the Department of Health recommendations for SIDS prevention has changed over the past 6 years, but the specific recommendations are largely consistent with the scientific evidence. The emphasis on thermal and illness factors and immunisation could be reduced. Bed sharing and sharing the parental bedroom should be given more emphasis. Two major recommendations need to be discussed in greater detail: (1) breast feeding and (2) pacifier use. Meta-analyses or reviews looking at each risk factor or a combination of risk factors are required. Further, it is recommended that a committee is established that reviews the recommendations and publishes the evidence that leads to these recommendations, as is done by the American Academy of Pediatrics Taskforce on Sudden Infant Death Syndrome.

Cardiac Sodium Channel Dysfunction in Sudden Infant Death Syndrome

BACKGROUND

Mutations in genes responsible for the congenital long-QT syndrome, especially SCN5A, have been identified in some cases of sudden infant death syndrome. In a large-scale collaborative genetic screen, several SCN5A variants were identified in a Norwegian sudden infant death syndrome cohort (n=201). We present functional characterization of 7 missense variants (S216L, R680H, T1304M, F1486L, V1951L, F2004L, and P2006A) and 1 in-frame deletion allele (delAL586-587) identified by these efforts.

METHODS AND RESULTS

Whole-cell sodium currents were measured in tsA201 cells transiently transfected with recombinant wild-type or mutant SCN5A cDNA (hH1) coexpressed with the human beta1 subunit. All variants exhibited defects in the kinetics and voltage dependence of inactivation. Five variants (S216L, T1304M, F1486L, F2004L, and P2006A) exhibited significantly increased persistent sodium currents (range, 0.5% to 1.7% of peak current) typical of SCN5A mutations associated with long-QT syndrome. These same 5 variants also displayed significant depolarizing shifts in voltage dependence of inactivation (range, 5 to 14 mV) and faster recovery from inactivation, but F1486L uniquely exhibits a depolarizing shift in the conductance-voltage relationship. Three alleles (delAL586-587, R680H, and V1951L) exhibited increased persistent current only under conditions of internal acidosis (R680H) or when expressed in the context of a common splice variant (delQ1077), indicating that they have a latent dysfunctional phenotype.

CONCLUSIONS

Our present results greatly expand the spectrum of functionally characterized SCN5A variants associated with sudden infant death syndrome and provide further biophysical correlates of arrhythmia susceptibility in this syndrome.

Differences in infant and parent behaviors during routine bed sharing compared with cot sleeping in the home setting

OBJECTIVES

To observe the behavior of infants sleeping in the natural physical environment of home, comparing the 2 different sleep practices of bed sharing and cot sleeping quantifying to factors that have been identified as potential risks or benefits.

METHODS

Forty routine bed-sharing infants, aged 5-27 weeks were matched for age and season of study with 40 routine cot-sleeping infants. Overnight video and physiologic data of bed-share infants and cot-sleep infants were recorded in the infants' own homes. Sleep time, sleep position, movements, feeding, blanket height, parental checks, and time out of the bed or cot were logged.

RESULTS

The total sleep time was similar in both groups (bed-sharing median: 8.6 hours; cot-sleeping median: 8.2 hours). Bed-sharing infants spent most time in the side position (median: 5.7 hours, 66% of sleep time) and most commonly woke at the end of sleep in this position, whereas cot-sleeping infants most commonly slept supine (median: 7.5 hours, 100%) and woke at the end of sleep in the supine position. Prone sleep was uncommon in both groups. Head covering above the eyes occurred in 22 bed-sharing infants and 1 cot-sleeping infant. Five of these bed-sharing infants were head covered at final waking time, but the cot-sleeping infant was not. Bed-sharing parents looked at or touched their infant more often (median: 11 vs 4 times per night) but did not always fully wake to do so. Movement episodes were shorter in the bed-sharing group as was total movement time (37 vs 50 minutes respectively), whereas feeding was 3.7 times more frequent in the bed-sharing group than the cot-sleeping group.

CONCLUSIONS

Bed-share infants without known risk factors for sudden infant death syndrome (SIDS) experience increased maternal touching and looking, increased breastfeeding, and faster and more frequent maternal responses. This high level of interaction is unlikely to occur if maternal arousal is impaired, for example, by alcohol or overtiredness. Increased head covering and side sleep position occur during bed-sharing, but whether these factors increase the risk of SIDS, as they do in cot sleeping, requires further investigation.

Smoking and the sudden infant death syndrome

The aims of this review are (a) to critically examine the epidemiologic evidence for a possible association between smoking and the sudden infant death syndrome (SIDS), (b) to review the pathology and postulated physiological mechanism(s) by which smoking might be causally related to SIDS, and (c) to provide recommendations for SIDS prevention in relation to tobacco smoking. Over 60 studies have examined the relation between maternal smoking during pregnancy and risk of SIDS. With regard to prone-sleep-position intervention programs, the pooled relative risk associated with maternal smoking was RR = 2.86 (95% CI = 2.77, 2.95) before and RR = 3.93 (95% CI = 3.78, 4.08) after. Epidemiologically, to distinguish the effect of active maternal smoking during pregnancy from involuntary tobacco smoking by the infants of smoking mothers is difficult. Clear evidence for environmental tobacco smoke exposure can be obtained by examining the risk of SIDS from paternal smoking when the mother is a non-smoker. Seven such studies have been carried out. The pooled unadjusted RR was 1.49 (95% CI = 1.25, 1.77). Consideration of the pathological and physiological effects of tobacco suggests that the predominant effect from maternal smoking comes from the in utero exposure of the fetus to tobacco smoke. Assuming a causal association between smoking and SIDS, about one-third of SIDS deaths might have been prevented if all fetuses had not been exposed to maternal smoking in utero.

Are the risk factors for SIDS different for preterm and term infants?

BACKGROUND

Mortality from SIDS has declined since the recommendation that infants are not placed prone to sleep. SIDS mortality is higher in infants born preterm than those born at term.

AIM

To determine if risk factors for SIDS are any different for preterm and term infants.

METHODS

Mortality data over time were used to determine whether the reduction in SIDS mortality rates had occurred equally in term and preterm infants. Data from two New Zealand studies (a case-control study and a case-cohort study) were used to determine if any differences existed in risk factors for SIDS between term and preterm infants before and after the SIDS prevention campaign.

RESULTS

SIDS mortality appears to have decreased by similar proportions in term and preterm infants. Risk factors for SIDS were similar in preterm and term infants, except for parity where there was a significant interaction. Increasing parity was a risk factor for SIDS in term infants but not preterm infants.

CONCLUSION

SIDS rates have decreased at comparable rates in term and preterm infants, but preterm birth still remains a risk factor for SIDS. The magnitude of the odds ratios associated with modifiable risk factors were similar for both groups. There may however be a difference in risk associated with parity between term and preterm infants. The messages for risk factors for SIDS are applicable to mothers of preterm as well as term infants.

Detection of specific antibodies in cord blood, infant and maternal saliva and breast milk to staphylococcal toxins implicated in sudden infant death syndrome (SIDS)

The common bacterial toxins hypothesis of sudden infant death syndrome (SIDS) is that nasopharyngeal bacterial toxins can trigger events leading to death in infants with absent/low levels of antibody that can neutralise the toxins. The aim of this study was to investigate nasopharyngeal carriage of Staphylococcus aureus and determine levels of immunity in the first year of life to toxic shock syndrome toxin (TSST-1) and staphylococcal enterotoxin C (SEC). Both toxins have been implicated in SIDS cases. Seventy-three mothers and their infants (39 males and 34 females) were enrolled onto the study. The infants had birth dates spread evenly throughout the year. In infants, S. aureus carriage decreased significantly with age (P<0.001). Between 40% and 50% of infants were colonised with S. aureus in the first three months of life and 49% of the isolates produced one or both of the staphylococcal toxins. There was a significant correlation between nasopharyngeal carriage of S. aureus in mothers and infants in the three months following the birth (P<0.001). Carriage of S. aureus in infants and their mothers was not significantly associated with levels of antibody to TSST-1 or SEC in cord blood, adult saliva or breast milk. Infants colonised by S. aureus had higher levels of salivary IgA to TSST-1 than infants who were culture negative. Analysis of cord blood samples by a quantitative ELISA detected IgG bound to TSST-1 and SEC in 95.5% and 91.8% of cases respectively. There was a marked variation in levels of maternal IgG to both TSST-1 and SEC among cord blood samples. Maternal age, birth weight, and seasonality significantly affected the levels of IgG binding to TSST-1 or SEC. Analysis of infant saliva samples detected IgA to TSST-1 and SEC in the first month after birth; 11% of samples tested positive for salivary IgA to TSST-1 and 5% for salivary IgA to SEC. By the age of two months these proportions had increased to 36% and 33% respectively. More infants who used a dummy tested positive for salivary IgA to TSST-1 compared to infants who did not use a dummy. Levels of IgA to TSST-1 and SEC detected in the breast-milk samples varied greatly among mothers. There was a trend for infants receiving breast milk with low levels of antibody to TSST-1 or SEC to have higher levels of salivary antibody to the toxins. In conclusion, passive immunity to toxins implicated in SIDS cases varies greatly among infants. Infants are able to mount an active mucosal immune response to TSST-1 and SEC in the first month of life.

Determinants of nonsynostotic plagiocephaly: a case-control study

OBJECTIVE

There has been a large increase in reported cases of nonsynostotic plagiocephaly in infants since the adoption of supine sleeping recommendations to prevent sudden infant death syndrome. The objective of this study was to identify and quantify the determinants of nonsynostotic plagiocephaly in infants.

METHODS

One hundred infants who received a diagnosis of having nonsynostotic plagiocephaly were recruited as case patients and compared with 94 control subjects who were selected from a citywide database of infants. The infants all were aged between 2 and 12 months. Information concerning sociodemographic variables, obstetric factors, infant factors, and infant care practices was obtained by parental interview.

RESULTS

Case patients were significantly more likely to be male (adjusted odds ratio [aOR]: 2.51; 95% confidence interval [CI]: 1.23-5.16), to be a firstborn (aOR: 2.94; 95% CI: 1.46-5.96), and to have been premature (aOR: 3.26; 95% CI: 1.02-10.47). In the first 6 weeks, they were more likely to have been sleeping in the supine position (aOR: 7.02; 95% CI: 2.98-16.53), not to have had the head position varied when put down to sleep (aOR: 7.11; 95% CI: 2.75-18.37), and to have had <5 minutes a day of tummy time (OR: 2.26; 95% CI: 1.03-5.00). Mothers of case patients were more likely to perceive their infants as less active (aOR: 3.23; 95% CI: 1.38-7.56), to have a developmental delay (aOR: 3.32; 95% CI: 1.01-10.85), and to have had a definite preferred head orientation at 6 weeks (aOR: 37.46; 95% CI: 8.44-166.32). Case mothers were more likely to have no or low educational qualifications (aOR: 5.61; 95% CI: 2.02-15.56), although they were more likely to have attended antenatal classes (aOR: 6.61; 95% CI: 1.59-27.47).

CONCLUSIONS

Early identification of a preferred head orientation, which may indicate the presence of neck muscle dysfunction, may help prevent the development or further development of nonsynostotic plagiocephaly in infants. Plagiocephaly might also be prevented by varying the head position when putting the very young infant down to sleep and by giving supervised tummy time when awake.