Postnatal parental smoking: an important risk factor for SIDS

Racial differences in the impact of maternal smoking on sudden unexpected infant death

BACKGROUND

Prenatal smoking increases the risk of Sudden Unexpected Infant Death (SUID). Whether exposure patterns and associations differ by race requires further study.

OBJECTIVES

Determine if patterns of exposure and associations between SUID and maternal smoking before and during pregnancy differ by race.

METHODS

Using U.S. National Center for Health Statistics linked birth/infant death files 2012-2013, we documented SUID by smoking duration and race. Maternal smoking history: never, pre-pregnancy only, and pre-pregnancy plus first, first, second, or all trimesters.

RESULTS

Smoking was more common in non-Hispanic White (NHW) than non-Hispanic Black (NHB) mothers and more evident for both in SUID cases. The most common exposure duration is from before and throughout pregnancy (SUID: 78.3% NHW, 66.9% NHB; Survivors: 60.22% and 53.96%, respectively). NHB vs. NHW SUID rates per 1000 live births were 1.07 vs. 0.34 for non-smokers and 3.06 and 1.79 for smokers, ORs trended upward for both with increasing smoking duration.

CONCLUSION

Fewer NHB mothers smoked, but both NHB and NHW groups exhibited a dose-response relationship between smoking duration and SUID. The most common duration was from before to the end of pregnancy, suggesting difficulty in quitting and a need for effective interventions.

Technical Report: Breastfeeding and the Use of Human Milk

Breastfeeding and human milk are the normative standards for infant feeding and nutrition. The short- and long-term medical and neurodevelopmental advantages of breastfeeding make breastfeeding or the provision of human milk a public health imperative. The American Academy of Pediatrics (AAP) recommends exclusive breastfeeding for approximately 6 months after birth. Furthermore, the AAP supports continued breastfeeding, along with appropriate complementary foods introduced at about 6 months, as long as mutually desired by mother and child for 2 years or beyond. These recommendations are consistent with those of the World Health Organization (WHO). Medical contraindications to breastfeeding are rare. The AAP recommends that birth hospitals or centers implement maternity care practices shown to improve breastfeeding initiation, duration, and exclusivity. The Centers for Disease Control and Prevention and The Joint Commission monitor breastfeeding practices in United States hospitals. Pediatricians play a critical role in hospitals, their practices, and communities as advocates of breastfeeding and, thus, need to be trained about the benefits of breastfeeding for mothers and children and in managing breastfeeding. Efforts to improve breastfeeding rates must acknowledge existing disparities and the impact of racism in promoting equity in breastfeeding education, support, and services.

Policy Statement: Breastfeeding and the Use of Human Milk

Breastfeeding and human milk are the normative standards for infant feeding and nutrition. The short- and long-term medical and neurodevelopmental advantages of breastfeeding make breastfeeding, or the provision of human milk, a public health imperative. The American Academy of Pediatrics (AAP) recommends exclusive breastfeeding for approximately 6 months after birth. Furthermore, the AAP supports continued breastfeeding, along with appropriate complementary foods introduced at about 6 months, as long as mutually desired by mother and child for 2 years or beyond. These recommendations are consistent with those of the World Health Organization (WHO). Medical contraindications to breastfeeding are rare. The AAP recommends that birth hospitals or centers implement maternity care practices shown to improve breastfeeding initiation, duration, and exclusivity. The Centers for Disease Control and Prevention (CDC) and The Joint Commission monitor breastfeeding practices in US hospitals. Pediatricians play a critical role in hospitals, their practices, and communities as advocates of breastfeeding and, thus, need to be trained about the benefits of breastfeeding for mothers and children and in managing breastfeeding.

Is There a Role for the Microbiome and Sudden Death? A Systematic Review

Background. Sudden unexpected death (SUD) is one of the most important and worthy investigation case profiles in emergency medicine and forensic pathology. Sudden unexpected deaths in adults (SUDA) are frequently caused by cardiac events, while infections usually cause those in infants younger than one year (SUDI), and to a lesser extent, in children older than one year (SUDC). However, in some instances of children under the age of one dying (SIDS), a cause is not discovered despite a thorough investigation that includes a review of clinical history, examination of the death scene, and a complete autopsy. Several studies demonstrate that the microbiome influences host immunity, alters susceptibility to viral respiratory infections, and has a vital role in various health, disease, and death outcomes. The main objective of this systematic review was to compile and offer a complete vision of the main lines of research on microbiome and sudden death that have emerged in recent years and their relationship with forensic sciences, as well as the possible contributions or limitations in the field of forensic sciences. Methods. Following PRISMA principles, a systematic evaluation of the microbiome and sudden death in forensic science was conducted. In this review, our study classified the sudden deaths as SUDA, SUDI, and SIDS. Results. The role of microbiome research in sudden death is discussed in this review. Various studies have linked the detection of different bacteria or viruses as a probable cause of sudden death. Bacteria analysed differ between studies that used autopsy specimens from deaths classified as SUDA, SUDI, and SIDS, or, except in the case of Staphylococcus aureus and Escherichia coli, which have been analysed in both SUDI and SIDS autopsies. In the case of viruses, only Cytomegalovirus has been analysed in both SIDS and SUDI cases. However, all the viruses studied are respiratory viruses found in samples of nasopharyngeal or lung fluid. Conclusions. Although the application of the microbiome in sudden death and other fields of forensic science is still in its early stages, a role of the microbiome in sudden deaths cannot be ruled out, but we cannot conclude that it is a significant factor either.

Knowledge Assessment of Correct Infant Sleep Practices and Sudden Infant Death Syndrome Among Mothers

INTRODUCTION

Sudden infant death syndrome (SIDS) is characterized as the sudden unexpected death of a healthy infant below the age of 12 months with an unknown cause even after careful death scene assessment. The aim of this study is to estimate the percentage of proper sleep practices among infants and assess the knowledge and awareness of SIDS and its associated risk factors among Saudi and non-Saudi mothers.

METHODS

This cross-sectional study was done in Riyadh, Saudi Arabia. The data were collected using an anonymous, self-administered questionnaire that consisted of 36 items that were divided into demographic data of the parents and child, observations of the child's sleep practice, and knowledge and awareness of SIDS and its associated risk factors.

RESULTS

A total of 667 participants completed the questionnaire. The mean age of the mothers was 31.44 + 7.55. As for the nationality, 527 (79%) were Saudi and 140 (21%) were non-Saudi. The majority had bachelors' degrees 407 (61%). Sleep practices assessment demonstrated that 391 (58.6%) of infants were sleeping in the supine position. A total of 329 (49.3%) participants reported hearing about SIDS from social media and websites as being the major source of information. SIDS acknowledgment was higher in non-Saudi mothers compared to Saudis.

CONCLUSION

The results provide informative descriptive data on childcare practices in Saudi Arabia. Considerable variation was noted and the results from this study are intended to have a better understanding of the prevalence of childcare practices and knowledge of SIDS risk factors in Saudi and non-Saudi mothers.

The Relationship Between Bonding Impairment and Maternal Postpartum Smoking

OBJECTIVES

Maternal postpartum smoking is associated with several negative outcomes for mother and child. The relationship between bonding impairment (BI) and maternal postpartum smoking is less known. The aim of the present study was to assess the relationship between BI and maternal postpartum smoking at 6 to 8 months after childbirth in a primary care sample of low-income mothers who had depression during the previous pregnancy.

METHODS

We performed a cross-sectional, secondary analysis from a community trial with 356 postpartum women from public primary care clinics in São Paulo, Brazil. The main outcome measure was maternal postpartum smoking. The main exposure variable was BI assessed with the Postpartum Bonding Questionnaire. A socio-demographic questionnaire evaluated maternal and obstetric characteristics. Postpartum depression was assessed with the Patient Health Questionnaire. Crude and adjusted prevalence ratios (PR) of the association between BI and maternal postpartum smoking, with 95% confidence intervals (CI), were calculated using Poisson regression. Multivariate analysis was performed using three models (Model 1 adjusted for randomization during pregnancy, Model 2 adjusted for Model 1 plus mother's socioeconomic and obstetric characteristics, and Model 3 adjusted for Model 2 plus postpartum depression).

RESULTS

Maternal postpartum smoking occurred in 16.7% of our sample. In the multivariable analysis, BI was associated with maternal postpartum smoking (PR:2.04; CI 95% 1.08:3.84).

CONCLUSIONS FOR PRACTICE

Women presenting bonding problems are at higher risk of smoking after childbirth. Intervention to enhance mother-child bonding may have the potential to decrease maternal postpartum smoking.

Toxic metals in human milk in relation to tobacco smoke exposure

Several reports confirm the deleterious effects of tobacco smoking and exposure to second-hand smoke (SHS) resulting in changes in the composition of breast milk. The aim of our study was to compare the levels of selected essential, as well as, toxic metals found in colostrum (collected at day 1 ± 2 post-birth) and mature milk (1 month ± 7 days post-birth) of nonsmoking women (n = 52) compared to those found in women who smoke tobacco (n = 51) and women exposed to second-hand smoke during pregnancy and lactation (n = 47). Women's non-smoking or smoking status was determined by their responses to a questionnaire, including questions about others who may smoke in the home environment, and confirmed by measurement of cotinine in the blood serum by high performance liquid chromatography with diode array detector (HPLC-DAD). Inductively coupled plasma mass spectrometry (ICP-MS) and flame atomic absorption spectroscopy (F-AAS) techniques were used to determine the metal concentrations in colostrum and mature milk previously digested by a microwave mineralizer. We confirmed that exposure to tobacco smoke increases concentrations of heavy metals (cadmium and lead) in colostrum and mature milk. These increased concentrations of heavy metals may disturb the action of bioactive substances necessary for the optimal growth and development of newborns and infants. These findings support the need for increased concern and information to lactating women about preventing their exposure to cigarette smoking and SHS due to the adverse effects of tobacco smoke on breast milk with added risks to their infants.

Duration of breastmilk feeding of NICU graduates who live with individuals who smoke

BACKGROUND

Breast milk has many benefits for infants, but initiating breastfeeding/pumping can be difficult for mothers of preterm infants, especially those who smoke (or live with individuals who smoke). The primary aim of this study was to identify risks for breastfeeding/pumping cessation with neonatal intensive care unit (NICU) infants' mothers who smoke or live with individuals who smoke, using a novel survival-analytic approach.

METHODS/DESIGN

Mothers (N = 360) were recruited for a secondhand smoke prevention intervention during infants' NICU hospitalizations and followed for ~6 months after infant discharge. Data were obtained from medical records and participant self-report/interviews.

RESULTS

The sample was predominantly ethnic/racial minorities; mean age was 26.8 (SD = 5.9) years. One-fifth never initiated breastfeeding/pumping (n = 67; 18.9%) and mean time-to-breastfeeding cessation was 48.1 days (SD = 57.2; median = 30.4 [interquartile range: 6.0-60.9]). Education, length of stay, employment, race/ethnicity, number of household members who smoke, and readiness-to-protect infants from tobacco smoke were significantly associated with breastfeeding cessation. Further, infants fed breast milk for ≥4 months had 42.7% more well-child visits (p < 0.001) and 50.0% fewer respiratory-related clinic visits (p < 0.05).

CONCLUSIONS

One-quarter of infants admitted to NICUs will be discharged to households where individuals who smoke live; we demonstrated that smoking-related factors were associated with mothers' breastfeeding practices. Infants who received breast milk longer had fewer respiratory-related visits.

IMPACT

One-quarter of NICU infants will be discharged to households where smokers live. Initiating/sustaining breastfeeding can be difficult for mothers of preterm NICU infants, especially mothers who smoke or live with others who smoke. Education, employment, race/ethnicity, length of stay, household member smoking, and readiness-to-protect infants from tobacco smoke were significantly associated with time-to-breastfeeding cessation. Infants fed breast milk for ≥4 months had 42.7% more well-child visits and 50.0% fewer respiratory-related clinic visits, compared to infants fed breast milk <4 months. Data support intervention refinements for mothers from smoking households and making NICU-based healthcare workers aware of risk factors for early breastfeeding cessation.

Are Safe Sleep Practice Recommendations For Infants Being Applied Among Caregivers?

Background

Sudden infant death syndrome (SIDS) is defined as the sudden unexpected death of an infant, even after investigations and autopsy. SIDS is related to many factors, such as the baby’s position and objects in the crib. Adherence to safe sleep recommendations in Saudi Arabia is unclear. This study aims to assess caregivers’ implementation of safe sleep practices and if they received any safe sleep education through health care workers.

Methods

This was a cross-sectional, descriptive study. Inclusion criteria included all infants below the age of one year. Exclusion criteria included infants who were born premature, used ventilation, had a tracheostomy, any anomaly in the upper airway, or underwent spine surgery. A semi-structured questionnaire was used. Data were collected from mothers who had infants visiting the outpatient department of King Abdulaziz University Hospital in Jeddah, Saudi Arabia. An electronic survey was also created and published on a social platform. 

Statistical analysis was conducted with the aid of the Statistical Package for Social Sciences (SPSS) software, version 26 (IBM SPSS Statistics, Armonk, NY).

Results

Among 506 participants, only 22.5% were found to receive education about safe practices from health care providers. Fortunately, most of the infants (63.2%) were found to sleep in a supine position most of the nights. Adherent caregivers to placing the child in a designated baby bed and in a supine position most nights represented 44.86% of the sample. However, when asked about placing any of the following objects in the bed (pillows, blankets, soft toys, hard toys, and electric wires), the percentage of adherence dropped down to only 1.58%.

Conclusion

There was an obvious non-adherence among caregivers and a possible lack of knowledge of safe sleep recommendations for infants. This highlights the need for optimal education by health care workers and the rule of media and campaigns is obvious and essential to improving their practices and, hopefully, decreasing the risk of SIDS.

Obstetricians' and Gynecologists' Communication Practices around Smoking Cessation in Pregnancy, Secondhand Smoke and Sudden Infant Death Syndrome (SIDS): A Survey

Secondhand smoke (SHS) is a potential direct cause of Sudden Infant Death Syndrome (SIDS) among infants. Disparities in SHS exposure and SIDS deaths may be due to inconsistent communication among practitioners about SHS/SIDS risks. In order to assess current SHS/SIDS risks and communication practices and to identify areas of improvement, we conducted a survey of 316 obstetricians and gynecologists (ob/gyns) about the length of time spent having discussions, supplemental materials used, risks covered, cessation, and frequency of discussions. Most (55.3%) reported spending 1-4 min discussing risks/cessation. Nearly a third reported not using any supplemental materials; few used apps (4.4%) or videos (1.9%). Assisting patients with steps toward cessation was infrequent. Few ob/gyns had discussions with patients immediately postpartum. Only 51.9% strongly agreed that they felt sufficiently informed about SHS/SIDS risks to educate their patients. The communication by ob/gyns of SHS/SIDS risk varies greatly and presents opportunities for improvement. Each additional minute spent having discussions and the use of supplemental materials, such as apps, may improve communication effectiveness. The discussion of smoking behaviors immediately postpartum may help to prevent smoker relapse. An increased awareness of statewide cessation resources by ob/gyns is needed to assist patients with cessation. The development of standardized risk messaging may reduce the variation in communication practices among ob/gyns.

Explaining sudden infant death with cardiac arrhythmias: Complete exon sequencing of nine cardiac arrhythmia genes in Dutch SIDS cases highlights new and known DNA variants

Previous studies suggested that Sudden Infant Death Syndrome (SIDS) can partially be genetically explained by cardiac arrhythmias; however, the number of individuals and populations investigated remain limited. We report the first SIDS study on cardiac arrhythmias genes from the Netherlands, a country with the lowest SIDS incidence likely due to parent education on awareness of environmental risk factors. By using targeted massively parallel sequencing (MPS) in 142 Dutch SIDS cases, we performed a complete exon screening of all 173 exons from 9 cardiac arrhythmias genes SCN5A, KCNQ1, KCNH2, KCNE1, KCNE2, CACNA1C, CAV3, ANK2 and KCNJ2 (∼34,000 base pairs), that were selected to harbour previously established SIDS-associated DNA variants. Motivated by the poor DNA quality from the paraffin embedded material used, the application of a conservative sequencing quality control protocol resulted in 102 SIDS cases surviving quality control. Amongst the 102 SIDS cases, we identified a total of 40 DNA variants in 8 cardiac arrhythmia genes found in 60 (58.8 %) cases. Statistical analyses using ancestry-adjusted reference population data and multiple test correction revealed that 13 (32.5 %) of the identified DNA variants in 6 cardiac arrhythmia genes were significantly associated with SIDS, which were observed in 15 (14.7 %) SIDS cases. These 13, and another three, DNA variants were classified as likely pathogenic for cardiac arrhythmias using the American College of Medical Genetics guidelines for interpretation of sequence variants. The 16 likely pathogenic DNA variants were found in 16 (15.7 %) SIDS cases, including i) 3 novel DNA variants not recorded in public databases ii) 7 known DNA variants for which significant SIDS association established here was previously unknown, and iii) 6 known DNA variants for which LQTS association was reported previously. By having replicated previously reported SIDS-associated DNA variants located in cardiac arrhythmia genes and by having highlighting novel SIDS-associated DNA variants in such genes, our findings provide additional empirical evidence for the partial genetic explanation of SIDS by cardiac arrhythmias. On a wider note, our study outcome stresses the need for routine post-mortem genetic screening of assumed SIDS cases, particularly for cardiac arrhythmia genes. When put in practise, it will allow preventing further sudden deaths (not only in infants) in the affected families, thereby allowing forensic molecular autopsy not only to provide answers on the cause of death, but moreover to save lives.

Maternal Implications of Breastfeeding: A Review for the Internist

Breastfeeding seems to be a low-cost intervention that provides both short- and long-term health benefits for the breastfeeding woman. Interventions to support breastfeeding can increase its rate, exclusivity, and duration. Internists often have a longitudinal relationship with their patients and can be important partners with obstetricians and pediatricians in advocating for breastfeeding. To play their unique and critical role in breastfeeding promotion, internists need to be knowledgeable about breastfeeding and its maternal health benefits. In this paper, we review the short- and long-term maternal health benefits of breastfeeding. We also discuss special considerations in the care of breastfeeding women for the internist.

Co-use of tobacco and marijuana during pregnancy: Pathways to externalizing behavior problems in early childhood

Use and co-use of tobacco and marijuana during pregnancy are associated with the development of social, cognitive, and behavioral problems for infants and children. However, less is known about the potential developmental impact of the use of tobacco and marijuana in tandem. The present study examined an etiological model for the development of externalizing behavior problems (EBP) in early childhood in a high risk sample (N = 247) of mother-infant dyads with prospective data from pregnancy to 36 months of child age. Co-use during pregnancy and continued maternal tobacco and marijuana use from infancy through early childhood were investigated. Although direct pathways from exposure during pregnancy to EBP were not significant, there was a significant indirect pathway from prenatal tobacco use to EBP via lower breastfeeding duration to lower maternal warmth/sensitivity to EBP, and a pathway from higher maternal affective dysregulation to higher EBP. These results highlight the importance of considering cascading effects of substance use during pregnancy on parental processes within the context of developmental risk and protection.

Assessment of tobacco smoke effects on neonatal cardiorespiratory control using a semi-automated processing approach

A semi-automated processing approach was developed to assess the effects of early postnatal environmental tobacco smoke (ETS) on the cardiorespiratory control of newborn lambs. The system consists of several steps beginning with artifact rejection, followed by the selection of stationary segments, and ending with feature extraction. This approach was used in six lambs exposed to 20 cigarettes/day for the first 15 days of life, while another six control lambs were exposed to room air. On postnatal day 16, electrocardiograph and respiratory signals were obtained from a 6-h polysomnographic recording. The effects of postnatal ETS exposure on heart rate variability, respiratory rate variability, and cardiorespiratory interrelations were explored. The unique results suggest that early postnatal ETS exposure increases respiratory rate variability and decreases the coupling between cardiac and respiratory systems. Potentially harmful consequences in early life include unstable breathing and decreased adaptability of cardiorespiratory function, particularly during early life challenges, such as prematurity or viral infection. Graphical abstract ᅟ.

Primary Care Opportunities to Prevent Unintentional Home Injuries: A Focus on Children and Older Adults

Unintentional injuries are a persistent public health problem in the United States. A new health care landscape has the potential to create a clinical environment that fosters greater involvement by health care providers in injury prevention. The aim of this article is to provide evidence supporting the need for engagement by primary care providers in unintentional home injury prevention along with examples of how this could be accomplished. We know a great deal about what population groups are at risk for certain types of injuries. We also know that many injuries can be prevented through policies, programs, and resources that ensure safe environments and promote safe behaviors. For example, the Centers for Disease Control and Prevention's STEADI (Stopping Elderly Accidents, Deaths, and Injuries) initiative comprises clinical decision support tools and educational materials for health care providers. Two effective interventions that have demonstrated a reduction in falls among children are the redesign of baby walkers (engineering) and the mandated use of window guards (enforcement). Primary care clinicians can play a key role in promoting their patient's safety. Taken collectively, a focused attention on preventing unintentional home injuries by primary care providers can contribute to the reduction of injuries and result in optimal health for all.

Risky Behaviors of Mothers with Infants on Sudden Infant Death Syndrome in Turkey

PURPOSE

Sudden infant death syndrome is the most common cause of death during the post-neonatal period. Factors such as sleeping position, bed sharing, pillow use, smoking during pregnancy and the breastfeeding period constitute risk factors for sudden infant death syndrome. This study aims to identify the risky behaviors of mothers with infants that may put their children at risk for sudden infant death syndrome.

DESIGN AND METHODS

This is a cross-sectional, descriptive study. Data were collected using a questionnaire that was developed by the researchers. The questionnaire was filled out by 456 mothers who applied to the family health center between October 2014 and January 2015.

RESULTS

The greatest risk factor is the infant's sleeping position. A total of 77.9% of the mothers put their babies in bed in a non-supine position; 65.8% used a pillow when they put their babies in bed, 52.9% used a soft mattress, and 28.5% shared their beds with their babies. Prone sleeping was more likely to occur when smoke was present in the home or a pillow was used.

CONCLUSION

Nurses should notify families of the risky behaviors that can cause sudden infant death syndrome and plan appropriate nursing care.

Intestinal Microbiota Composition in Sudden Infant Death Syndrome and Age-Matched Controls

OBJECTIVE

To assess whether features of the infant intestinal microbiome, including the carriage of toxigenic bacteria, are associated with sudden infant death syndrome (SIDS).

STUDY DESIGN

We undertook a case-controlled analysis of fecal microbiology in SIDS. Fecal material was obtained from 44 cases and 44 aged-matched controls. Microbiota composition was determined by 16S ribosomal RNA gene amplicon sequencing and comparisons between cases and controls made based on both bacterial alpha diversity measures and unconstrained ordination. Specific quantitative polymerase chain reaction assays were used to determine intestinal carriage of Staphylococcus aureus, toxigenic Clostridium difficile, and pathogenic and nonpathogenic Escherichia coli.

RESULTS

The microbial composition for the study population as a whole was consistent with previous studies of infants <12 months of age, with a correlation between alpha diversity and age (r² = 0.08; P = .007). However, no difference was observed in alpha diversity between SIDS cases and controls (P > .4). Nonmetric multidimensional scaling also revealed no evidence of differences in microbiota dispersal between SIDS cases and controls (P = .4, permutational multivariate ANOVA test; Pseudo-F = 0.9), nor was a difference observed in microbiota dispersion (P = .19, PERMDISP test; F = 1.9). There were no significant intergroup differences in the carriage of S aureus, toxigenic C difficile, total E coli, or pathogenic E coli.

CONCLUSIONS

We found no evidence of an association between altered intestinal microbiology and SIDS, or to support the development of strategies to reduce the incidence of SIDS that target intestinal microbiology.

Pituitary adenylate cyclase activating polypeptide (PACAP) and its receptor 1 (PAC1) in the human infant brain and changes in the Sudden Infant Death Syndrome (SIDS)

Pituitary adenylate cyclase activating polypeptide (PACAP) and its complementary receptor, PAC1, are crucial in central respiratory control. PACAP Knockout (KO) mice exhibit a SIDS-like phenotype, with an inability to overcome noxious insults, compression of baseline ventilation, and death in the early post-neonatal period. PAC1 KO demonstrate similar attributes to PACAP-null mice, but with the addition of increased pulmonary artery pressure, consequently leading to heart failure and death. This study establishes a detailed interpretation of the neuroanatomical distribution and localization of both PACAP and PAC1 in the human infant brainstem and hippocampus, to determine whether any changes in expression are evident in infants who died of Sudden Infant Death Syndrome (SIDS) and any relationships to risk factors of SIDS including smoke exposure and sleep related parameters. Immunohistochemistry for PACAP and PAC1 was performed on formalin fixed and paraffin embedded human infant brain tissue of SIDS (n=32) and non-SIDS (n=12). The highest expression of PACAP was found in the hypoglossal (XII) of the brainstem medulla and lowest expression in the subiculum of the hippocampus. Highest expression of PAC1 was also found in XII of the medulla and lowest in the midbrain dorsal raphe (MBDR) and inferior colliculus. SIDS compared to non-SIDS had higher PACAP in the MBDR (p<0.05) and lower PAC1 in the medulla arcuate nucleus (p<0.001). Correlations were found between PACAP and PAC1 with the risk factors of smoke exposure, bed sharing, upper respiratory tract infection (URTI) and seasonal temperatures. The findings of this study show for the first time that some abnormalities of the PACAP system are evident in the SIDS brain and could contribute to the mechanisms of infants succumbing to SIDS.

Environmental risk factors for sudden infant death syndrome in Japan

While the prevalence of sudden infant death syndrome (SIDS) has decreased worldwide, this decline has plateaued recently. Strategies are needed to resume the constant decrease of SIDS in Japan. A prospective electrocardiographic screening program for infants was performed between July 2010 and March 2011. Parents of 4319 infants were asked about environmental factors related to SIDS through questionnaires at a one-month medical checkup and one year. Parental awareness of prone position, smoke exposure, and breast feeding as environmental factors were 81.4 %, 69.0 %, and 47.8 %, respectively. The prevalence of laying infants exclusively in a supine position was 96.7 %. At the one-month medical checkup, smoking prevalence was 41.7 % in fathers and 2.1 % in mothers. Maternal smoking prevalence was significantly increased at one year after (p < 0.001). Multivariate regression analysis showed that risk factors for new or continued maternal smoking habits were maternal smoking habits at one month (p < 0.001), paternal smoking habits one year later (p < 0.001), and younger maternal age (p = 0.02).

CONCLUSION

Most parents already avoid laying infants in the prone position, and parental smoking is still a SIDS risk concern in Japan. Smoking cessation programs should be further implemented for parents to decrease risks of SIDS in Japan. What is Known: • The prevalence of sudden infant death syndrome (SIDS) has decreased worldwide, however, this decline has plateaued recently. What is New: • Most infants were laid sleeping in the supine position (96.7 %) and were fed breast milk or a mix of expressed milk and formula (92.7 %), and 2.1 % of mothers smoked at the one-month medical checkup. • Maternal smoking prevalence significantly increased from the one-month medical checkup to one year later, and smoking mothers were more likely to feed infants by formula rather than breast milk. • Independent risk factors for new or continued maternal smoking habits included younger maternal age, maternal smoking habits at one month, and paternal smoking habits one year later.

Tobacco smoking and breastfeeding: Effect on the lactation process, breast milk composition and infant development. A critical review

Approximately 10% of women report smoking during pregnancy. The number of breastfeeding women who relapse back to smoking is even greater. Smoking may cause adverse changes to the milk's composition by not only reducing its protective properties, but also by affecting the infant's health. The pathophysiological mechanisms underlying these adverse effects are not entirely known. This article is a review of previous reports about the effects of smoking on the lactation process, breast milk composition and infant development. A systematic search for English language articles published until 2015 was made, using a MEDLINE data. The key search terms were "smoking and breastfeeding", "smoking and lactation", "smoking and milk composition", "nicotine and breast milk". Studies have shown that nicotine levels in breast milk of women who smoke are three times higher than those in the plasma levels. Breast milk volume is reduced and the duration of lactation period is shorter. Smoking causes adverse changes to the milk's composition by not only reducing its protective properties, but also affecting infants' response to breastfeeding and to breast milk.

Independent and combined effects of maternal smoking and solid fuel on infant and child mortality in sub-Saharan Africa

OBJECTIVE

To estimate the independent and combined risks of infant and child mortality associated with maternal smoking and use of solid fuel in sub-Saharan Africa.

METHODS

Pooled weighted data on 143 602 under-five children in the most recent demographic and health surveys for 15 sub-Saharan African countries were analysed. The synthetic cohort life table technique and Cox proportional hazard models were employed to investigate the effect of maternal smoking and solid cooking fuel on infant (age 0-11 months) and child (age 12-59 months) mortality. Socio-economic and other confounding variables were included as controls.

RESULTS

The distribution of the main explanatory variable in households was as follows: smoking + solid fuel - 4.6%; smoking + non-solid fuel - 0.22%; no smoking + solid fuel - 86.9%; and no smoking + non-solid fuel - 8.2%. The highest infant mortality rate was recorded among children exposed to maternal smoking + solid fuel (72 per 1000 live births); the child mortality rate was estimated to be 54 per 1000 for this group. In full multivariate models, the risk of infant death was 71% higher among those exposed to maternal smoking + solid fuel (HR = 1.71, CI: 1.29-2.28). For ages 12 to 59 months, the risk of death was 99% higher (HR = 1.99, CI: 1.28-3.08).

CONCLUSIONS

Combined exposures to cigarette smoke and solid fuel increase the risks of infant and child mortality. Mothers of under-five children need to be educated about the danger of smoking while innovative approaches are needed to reduce the mortality risks associated with solid cooking fuel.

Intrauterine Tobacco Smoke Exposure and Congenital Heart Defects

Tobacco use and second-hand smoke exposure during pregnancy are linked to a host of deleterious effects on the pregnancy, fetus, and infant. Health outcomes improve when women quit smoking at any time during the pregnancy. However, the developing heart is vulnerable to noxious stimuli in the early weeks of fetal development, a time when many women are not aware of being pregnant. Congenital heart defects are the most common birth defects. Research shows an association between maternal tobacco exposure, both active and passive, and congenital heart defects. This article presents recent evidence supporting the association between intrauterine cigarette smoke exposure in the periconceptional period and congenital heart defects and discusses clinical implications for practice for perinatal and neonatal nurses.

Public Policy to Protect Children From Tobacco, Nicotine, and Tobacco Smoke

Tobacco use and tobacco smoke exposure are among the most important health threats to children, adolescents, and adults. There is no safe level of tobacco smoke exposure. The developing brains of children and adolescents are particularly vulnerable to the development of tobacco and nicotine dependence. Tobacco is unique among consumer products in that it causes disease and death when used exactly as intended. Tobacco continues to be heavily promoted to children and young adults. Flavored and alternative tobacco products, including little cigars, chewing tobacco, and electronic nicotine delivery systems are gaining popularity among youth. This statement describes important evidence-based public policy actions that, when implemented, will reduce tobacco product use and tobacco smoke exposure among youth and, by doing so, improve the health of children and young adults.

Clinical Practice Policy to Protect Children From Tobacco, Nicotine, and Tobacco Smoke

Tobacco dependence starts in childhood. Tobacco exposure of children is common and causes illness and premature death in children and adults, with adverse effects starting in the womb. There is no safe level of tobacco smoke exposure. Pediatricians should screen for use of tobacco and other nicotine delivery devices and provide anticipatory guidance to prevent smoking initiation and reduce tobacco smoke exposure. Pediatricians need to be aware of the different nicotine delivery systems marketed and available.Parents and caregivers are important sources of children's tobacco smoke exposure. Because tobacco dependence is a severe addiction, to protect children's health, caregiver tobacco dependence treatment should be offered or referral for treatment should be provided (such as referral to the national smoker's quitline at 1-800-QUIT-NOW). If the source of tobacco exposure cannot be eliminated, counseling about reducing exposure to children should be provided.Health care delivery systems should facilitate the effective prevention, identification, and treatment of tobacco dependence in children and adolescents, their parents, and other caregivers. Health care facilities should protect children from tobacco smoke exposure and tobacco promotion. Tobacco dependence prevention and treatment should be part of medical education, with knowledge assessed as part of board certification examinations.

Protecting Children From Tobacco, Nicotine, and Tobacco Smoke

This technical report serves to provide the evidence base for the American Academy of Pediatrics' policy statements "Clinical Practice Policy to Protect Children From Tobacco, Nicotine, and Tobacco Smoke" and "Public Policy to Protect Children From Tobacco, Nicotine, and Tobacco Smoke." Tobacco use and involuntary exposure are major preventable causes of morbidity and premature mortality in adults and children. Tobacco dependence almost always starts in childhood or adolescence. Electronic nicotine delivery systems are rapidly gaining popularity among youth, and their significant harms are being documented. In utero tobacco smoke exposure, in addition to increasing the risk of preterm birth, low birth weight, stillbirth, placental abruption, and sudden infant death, has been found to increase the risk of obesity and neurodevelopmental disorders. Actions by pediatricians can help to reduce children's risk of developing tobacco dependence and reduce children's involuntary tobacco smoke exposure. Public policy actions to protect children from tobacco are essential to reduce the toll that the tobacco epidemic takes on our children.

Sudden infant death syndrome and residential altitude

BACKGROUND

Theories of sudden infant death syndrome (SIDS) suggest hypoxia is a common pathway. Infants living at altitude have evidence of hypoxia; however, the association between SIDS incidence and infant residential altitude has not been well studied.

METHODS

We performed a retrospective cohort study by using data from the Colorado birth and death registries from 2007 to 2012. Infant residential altitude was determined by geocoding maternal residential address. Logistic regression was used to determine adjusted association between residential altitude and SIDS. We evaluated the impact of the Back to Sleep campaign across various altitudes in an extended cohort from 1990 to 2012 to assess for interaction between sleep position and altitude.

RESULTS

A total of 393 216 infants born between 2007 and 2012 were included in the primary cohort (51.4% boys; mean birth weight 3194 ± 558 g). Overall, 79.6% infants resided at altitude <6000 feet, 18.5% at 6000 to 8000 feet, and 1.9% at >8000 feet. There were no meaningful differences in maternal characteristics across altitude groups. Compared with residence <6000 feet, residence at high altitude (>8000 feet), was associated with an adjusted increased risk of SIDS (odds ratio 2.30; 95% confidence interval 1.01-5.24). Before the Back to Sleep campaign, the incidence of SIDS in Colorado was 1.99/1000 live births and dropped to 0.57/1000 live births after its implementation. The Back to Sleep campaign had similar effect across different altitudes (P = .45).

CONCLUSIONS

Residence at high altitude was significantly associated with an increased adjusted risk for SIDS. Impact of the Back to Sleep campaign was similar across various altitudes.

Men's Responses to Online Smoking Cessation Resources for New Fathers: The Influence of Masculinities

Background

Smoking cessation is the single most important step to preventing cancer. Drawing on previous research, Web-based resources were developed to complement a program to support expectant and new fathers to quit smoking.

Objective

The objectives of this research were to: (1) describe the responses of expectant and new fathers who smoke or had recently quit smoking to the website resources, and (2) explore how masculinities shape men’s responses to and experiences with online smoking cessation resources.

Methods

Using semi-structured, individual face-to-face interviews, the Dads in Gear Web-based resources were reviewed and evaluated by 20 new fathers who smoked or had recently quit smoking. The data were transcribed and analyzed using NVivo 8 qualitative data analysis software.

Results

We describe the fathers’ reactions to various components of the website, making connections between masculinities and fathering within 5 themes: (1) Fathering counts: gender-specific parenting resources; (2) Measuring up: bolstering masculine identities as fathers; (3) Money matters: triggering masculine virtues related to family finances; (4) Masculine ideals: father role models as cessation aids; and (5) Manly moves: physical activity for the male body.

Conclusions

A focus on fathering was an effective draw for men to the smoking cessation resources. The findings provide direction for considering how best to do virtual cessation programs as well as other types of online cancer prevention programs for men.

Bed Sharing, SIDS Research, and the Concept of Confounding: A Review for Public Health Nurses

Confounding is an important concept for public health nurses (PHNs) to understand when considering the results of epidemiological research. The term confounding is derived from Latin, confundere, which means to "mix-up" or "mix together". Epidemiologists attempt to derive a cause and effect relationship between two variables traditionally known as the exposure and disease (e.g., smoking and lung cancer). Confounding occurs when a third factor, known as a confounder, leads to an over- or underestimate of the magnitude of the association between the exposure and disease. An understanding of confounding will facilitate critical appraisal of epidemiological research findings. This knowledge will enable PHNs to strengthen their evidence-based practice and better prepare them for policy development and implementation. In recent years, researchers and clinicians have examined the relationship between bed sharing and sudden infant death syndrome (SIDS). The discussion regarding the risk of bed sharing and SIDS provides ample opportunity to discuss the various aspects of confounding. The purpose of this article is to use the bed sharing and SIDS literature to assist PHNs to understand confounding and to apply this knowledge when appraising epidemiological research. In addition, strategies that are used to control confounding are discussed.

Animal models for assessment of infection and inflammation: contributions to elucidating the pathophysiology of sudden infant death syndrome

Sudden infant death syndrome (SIDS) is still not well understood. It is defined as the sudden and unexpected death of an infant without a definitive cause. There are numerous hypotheses about the etiology of SIDS but the exact cause or causes have never been pinpointed. Examination of theoretical pathologies might only be possible in animal models. Development of these models requires consideration of the environmental and/or developmental risk factors often associated with SIDS, as they need to explain how the risk factors could contribute to the cause of death. These models were initially developed in common laboratory animals to test various hypotheses to explain these infant deaths – guinea pig, piglet, mouse, neonatal rabbit, and neonatal rat. Currently, there are growing numbers of researchers using genetically altered animals to examine specific areas of interest. This review describes the different systems and models developed to examine the diverse hypotheses for the cause of SIDS and their potential for defining a causal mechanism or mechanisms.

Incidence and determinants of sudden infant death syndrome: a population-based study on 37 million births

BACKGROUND

The objective of our study is to measure the incidence of sudden infant death syndrome (SIDS), estimate the birth to death interval, and identify associated maternal and infant risk factors.

METHODS

We carried out a population-based cohort study on 37 418 280 births using data from the Centers for Disease Control and Prevention's "Linked Birth-Infant Death" and "Fetal Death" data files from 1995 to 2004. Descriptive statistics and cox-proportional hazard models were used to estimate the adjusted effect of maternal and newborn characteristics on the risk of SIDS.

RESULTS

There were 24 101 cases of SIDS identified for an overall 10-year incidence of 6.4 cases per 10 000 births. Over the study period, the incidence decreased from 8.1 to 5.6 per 10 000 and appeared to be most common among infants aged 2-4 months. Risk factors included maternal age <20 years, black, non-Hispanic race, smoking, increasing parity, inadequate prenatal care, prematurity and growth restriction.

CONCLUSIONS

While the incidence of SIDS in the US has declined, it currently remains the leading cause of post-neonatal mortality, highlighting an important public health priority. Educational campaigns should be targeted towards mothers at increased risk in order to raise their awareness of modifiable risk factors for SIDS such as maternal smoking and inadequate prenatal care.

Unintentional home injuries across the life span: problems and solutions

Home injuries cause more than 30,000 deaths and 12 million nonfatal injuries annually in the United States. They generate an estimated $222 billion in lifetime costs annually. Despite some data limitations in documenting home as the location of an injury, much progress has been made in identifying effective prevention strategies that reduce injury or mitigate risk behaviors. The current interest in public health in the role of housing in health offers unparalleled opportunities for injury prevention professionals concerned with home injuries. Sharing the science of injury prevention with the wide array of professionals-such as architects, home builders, home visitors, and fire and emergency medical services providers-who create home environments and interact with residents could be a useful approach. A collaborative national effort to reduce the burden of home injuries is needed.

Adverse circulatory effects of passive smoking during infancy: surprisingly strong, manifest early, easily avoided

AIM

To compare blood pressure reactions (BPR) of infants to mild stress for evidence of adverse cardiovascular effects of passive exposure to tobacco smoke during pregnancy and early infancy.

METHODS

An observational field study conducted in Crete. We compared 4- to 6-month olds of lifelong nonsmokers minimally (controls, n = 9) or frequently exposed to tobacco smoke (passive smokers; n = 10) with those born to habitual smokers (n = 6). Smoke exposure was verified biochemically (urine cotinine each trimester and at study). We recorded beat-to-beat blood pressure (BP) during brief repositioning manoeuvres performed during a daytime nap and analysed BPR (% change in BP during head-up tilt) for associations with maternal and infant cotinine.

RESULTS

We observed a 20-fold difference between BPR of infants of controls versus passive smokers - exceptional given number of infants (α error/confidence level <10% i.e. power >90%). The BPR declined linearly as the infant's (but not mother's) cotinine level rose (p = 0.04), indicating abnormal BPR was caused mainly by postnatal smoke exposure. Infants of active smokers differed from those of passive smokers.

CONCLUSION

Cardiovascular effects of passive smoking by a newborn infant manifest early on and are exceptionally strong. They can be largely avoided by keeping the home smoke rigorously free.

Sodium/proton exchanger 3 (NHE3) and sudden infant death syndrome (SIDS)

The sodium/proton exchanger protein 3 (NHE3) is located in chemosensitive areas of the medulla oblongata and plays an important role in the central control of respiration. Overexpression of NHE3 is correlated with lower respiration and might therefore contribute to the vulnerability of infants dying suddenly and unexpected (sudden infant death syndrome, SIDS). Our aim in this study was to verify already reported genetic variations in the NHE3 gene in an independent SIDS cohort from Switzerland. Two single nucleotide polymorphisms (SNPs) in the promoter region (G1131A and C1197T) and one variation in the coding sequence of exon 16 (C2405T) in the NHE3 gene were analyzed in 160 Caucasian SIDS infants and 192 Swiss adult controls by using a single base extension method (SNaPshot multiplex). No significant differences were detected in the allelic frequencies of the three NHE3 polymorphisms between SIDS cases and controls. We conclude that the three investigated NHE3 SNPs are unlikely to play a major role in the pathogenesis of SIDS in Caucasian infants. However, further genetic investigations in different ethnicities are required to determine whether variations in NHE3 are associated with an increased SIDS risk.

Clinical Implications of Impaired Sleep

Despite its pervasiveness in primary care, deficient sleep often is underappreciated as a cue to other health risks. Accordingly, this review discusses contemporary evidence-based perspectives on impaired sleep and its associations with other lifestyle medicine concerns, including obesity, cardiovascular conditions, psychological problems, and health-compromising habits. The potential clinical benefits of promoting sleep health also will be considered.

PHOX2B polyalanine repeat length is associated with sudden infant death syndrome and unclassified sudden infant death in the Dutch population

Unclassified sudden infant death (USID) is the sudden and unexpected death of an infant that remains unexplained after thorough case investigation including performance of a complete autopsy and review of the circumstances of death and the clinical history. When the infant is below 1 year of age and with onset of the fatal episode apparently occurring during sleep, this is referred to as sudden infant death syndrome (SIDS). USID and SIDS remain poorly understood despite the identification of several environmental and some genetic risk factors. In this study, we investigated genetic risk factors involved in the autonomous nervous system in 195 Dutch USID/SIDS cases and 846 Dutch, age-matched healthy controls. Twenty-five DNA variants from 11 genes previously implicated in the serotonin household or in the congenital central hypoventilation syndrome, of which some have been associated with SIDS before, were tested. Of all DNA variants considered, only the length variation of the polyalanine repeat in exon 3 of the PHOX2B gene was found to be statistically significantly associated with USID/SIDS in the Dutch population after multiple test correction. Interestingly, our data suggest that contraction of the PHOX2B exon 3 polyalanine repeat that we found in six of 160 SIDS and USID cases and in six of 814 controls serves as a probable genetic risk factor for USID/SIDS at least in the Dutch population. Future studies are needed to confirm this finding and to understand the functional effect of the polyalanine repeat length variation, in particular contraction, in exon 3 of the PHOX2B gene.

The transfer of drugs and therapeutics into human breast milk: an update on selected topics

Many mothers are inappropriately advised to discontinue breastfeeding or avoid taking essential medications because of fears of adverse effects on their infants. This cautious approach may be unnecessary in many cases, because only a small proportion of medications are contraindicated in breastfeeding mothers or associated with adverse effects on their infants. Information to inform physicians about the extent of excretion for a particular drug into human milk is needed but may not be available. Previous statements on this topic from the American Academy of Pediatrics provided physicians with data concerning the known excretion of specific medications into breast milk. More current and comprehensive information is now available on the Internet, as well as an application for mobile devices, at LactMed (http://toxnet.nlm.nih.gov). Therefore, with the exception of radioactive compounds requiring temporary cessation of breastfeeding, the reader will be referred to LactMed to obtain the most current data on an individual medication. This report discusses several topics of interest surrounding lactation, such as the use of psychotropic therapies, drugs to treat substance abuse, narcotics, galactagogues, and herbal products, as well as immunization of breastfeeding women. A discussion regarding the global implications of maternal medications and lactation in the developing world is beyond the scope of this report. The World Health Organization offers several programs and resources that address the importance of breastfeeding (see http://www.who.int/topics/breastfeeding/en/).

Bed sharing when parents do not smoke: is there a risk of SIDS? An individual level analysis of five major case-control studies

OBJECTIVE

To resolve uncertainty as to the risk of Sudden Infant Death Syndrome (SIDS) associated with sleeping in bed with your baby if neither parent smokes and the baby is breastfed.

DESIGN

Bed sharing was defined as sleeping with a baby in the parents' bed; room sharing as baby sleeping in the parents' room. Frequency of bed sharing during last sleep was compared between babies who died of SIDS and living control infants. Five large SIDS case-control datasets were combined. Missing data were imputed. Random effects logistic regression controlled for confounding factors.

SETTING

Home sleeping arrangements of infants in 19 studies across the UK, Europe and Australasia.

PARTICIPANTS

1472 SIDS cases, and 4679 controls. Each study effectively included all cases, by standard criteria. Controls were randomly selected normal infants of similar age, time and place.

RESULTS

In the combined dataset, 22.2% of cases and 9.6% of controls were bed sharing, adjusted OR (AOR) for all ages 2.7; 95% CI (1.4 to 5.3). Bed sharing risk decreased with increasing infant age. When neither parent smoked, and the baby was less than 3 months, breastfed and had no other risk factors, the AOR for bed sharing versus room sharing was 5.1 (2.3 to 11.4) and estimated absolute risk for these room sharing infants was very low (0.08 (0.05 to 0.14)/1000 live-births). This increased to 0.23 (0.11 to 0.43)/1000 when bed sharing. Smoking and alcohol use greatly increased bed sharing risk.

CONCLUSIONS

Bed sharing for sleep when the parents do not smoke or take alcohol or drugs increases the risk of SIDS. Risks associated with bed sharing are greatly increased when combined with parental smoking, maternal alcohol consumption and/or drug use. A substantial reduction of SIDS rates could be achieved if parents avoided bed sharing.

Histological findings in unclassified sudden infant death, including sudden infant death syndrome

Our objective was to study histological variations and abnormalities in unclassified sudden infant death (USID), including sudden infant death syndrome (SIDS), in The Netherlands. Two hundred Dutch USID cases between 1984 and 2005 were identified. The histology slides and autopsy reports of 187 cases were available for systematic review, including brain autopsy in 135 cases. An explanation for the cause of death in 19 patients (10.2%) was found. Twelve patients had bronchopneumonia, 3 showed extensive aspiration, 2 had signs of a metabolic disorder, 1 had sepsis, and 1 had meningitis. Frequent nonspecific findings were congestion (66%), edema (47%), small hemorrhages (18%), and lymphoid aggregates (51%) in the lungs; congestion of the liver (23%); and asphyctic bleeding in the kidney (44%), adrenal gland (23%), and thymus (17%). Statistical associations were found for infection with starry sky macrophages in the thymus (P  =  0.004), with calcification (P  =  0.023), or with debris in the Hassal's corpuscles (P  =  0.034). In this study, in 10.2% of cases the histological findings were incompatible with SIDS or USID. Furthermore, several frequent nonspecific histological findings in the thymus that point toward an infection were found.

Effects of postnatal environmental tobacco smoke on non-nutritive swallowing-breathing coordination in newborn lambs

While prenatal environmental tobacco smoke (ETS) exposure is a well-known risk factor for sudden infant death syndrome, the effect of postnatal ETS exposure is less clear. The objective of this study was to investigate the effect of postnatal ETS exposure on non-nutritive swallowing (NNS) and NNS-breathing coordination, which are crucial to prevent aspiration related-cardiorespiratory events. Eighteen newborn lambs (6 per group) were randomly exposed to either 10 cigarettes/day, 20 cigarettes/day or room air for 15 days. Lambs were instrumented for recording states of alertness, swallowing, electrocardiogram and breathing; recordings were performed in non-sedated lambs at the end of ETS exposure. Urinary cotinine/creatinine ratio confirmed relevant real-life exposure. Postnatal ETS exposure had no effect on NNS frequency but tended to decrease inspiratory NNS (p=0.07) during quiet sleep. No effect on respiratory or heart rate (p>0.6), apnea index (p=0.2) or sleep states (p=0.3) was observed. In conclusion, postnatal ETS exposure in lambs had only mild effects on NNS-breathing coordination.

Maternal smoking and increased risk of sudden infant death syndrome: a meta-analysis

Maternal smoking is detrimental to the development of fetuses and neonates. This meta-analysis was performed to measure the accumulated association of sudden infant death syndrome (SIDS) risk with both prenatal and postnatal maternal smoking. The odds ratio (OR) corresponding to the 95% confidence interval (CI) was used to assess the associations between maternal smoking and SIDS risk. The statistical heterogeneity among studies was assessed with the Q-test and I(2) statistics. The data for this meta-analysis were available from 35 case-control studies. The prenatal and postnatal maternal smoking was associated with a significantly increased risk of SIDS (OR=2.25, 95% CI=2.03-2.50 for prenatal maternal smoking analysis, and OR=1.97, 95% CI=1.77-2.19 for postnatal maternal smoking analysis, respectively) by random effects model. After stratified analyses, regardless of prenatal or postnatal smoking, heavy cigarette consumption increased the risk of SIDS and significantly elevated SIDS risk was found to be associated with co-sleeping with postnatal smoking mothers. Our results suggested that maternal smoking were associated with elevated SIDS risk, the effects were dose-dependent. In addition, SIDS risk was significantly increased in infants co-sleeping with postnatal smoking mothers.