Maternal smoking: an increasing unique risk factor for sudden infant death syndrome in Sweden

Ventilatory response to added dead space in infants exposed to second-hand smoke in pregnancy

Maternal cigarette smoking in pregnancy can adversely affect infant respiratory control. In utero nicotine exposure has been shown to blunt the infant ventilatory response to hypercapnia, which could increase the risk of sudden infant death syndrome. The potential impact of maternal second-hand smoke exposure, however, has not yet been determined. The aim of this study was to assess ventilatory response to added dead-space (inducing hypercapnia) in infants with second-hand smoke exposure during pregnancy, in infants whose mothers smoked and in controls (non-smoke exposed). Infants breathed through a face mask and specialised "tube-breathing" circuit, incorporating a dead space of 4.4 ml/kg body weight. The maximum minute ventilation (MMV) during added dead space breathing was determined and the time taken to achieve 63% of the MMV calculated (the time constant (TC) of the response). Infants were studied on the postnatal ward prior to discharge home. Thirty infants (ten in each group) were studied with a median gestational age of 39 [range 37-41] weeks, birthweight of 3.1 [2.2-4.0] kg, and postnatal age of 33 (21-62) h. The infants whose mothers had second-hand smoke exposure (median TC 42 s, p = 0.001), and the infants of cigarette smoking mothers (median TC 37 s, p = 0.002) had longer time constants than the controls (median TC 29 s). There was no significant difference between the TC of the infants whose mothers had second-hand smoke exposure and those whose mothers smoked (p = 0.112).    Conclusion: Second-hand smoke exposure during pregnancy was associated with a delayed newborn ventilatory response. What is Known: • Maternal cigarette smoking in pregnancy can adversely affect infant respiratory control. • The potential impact of maternal second-hand smoke exposure, however, has not yet been determined. What is New: • We have assessed the ventilatory response to added dead-space (inducing hypercapnia) in newborns with second-hand smoke exposure during pregnancy, in infants whose mothers smoked, and in controls (non-smoke exposed). • Maternal second-hand smoke exposure, as well as maternal smoking, during pregnancy was associated with a delayed newborn ventilatory response.

Factors Associated with Safe Infant Sleep Practices in Saudi Arabia

Purpose

To assess mothers’ approaches to infant sleep practices.

Patients and Methods

A cross-sectional survey study was conducted on mothers with babies aged below five months who were attending paediatric clinics between November 1st, 2020, and January 5th, 2021, in Riyadh, Saudi Arabia.

Results

A total of 522 mothers participated in this study. A total of 38.9% practised exclusive formula feeding. A total of 61.9% of the participants practised the supine position. The majority (93.3%) of the mothers shared a room with their babies, while 34.7% shared a bed. Only 6.9% did not use any soft bedding. Age was a significant predictor associated with participant practices regarding sleeping and feeding positions (p < 0.05). Having two or more children was associated with improper sleeping practices (p < 0.05). Being non-Saudi and having a university degree or higher were associated with having a higher risk of unsafe practices regarding bed-sharing (p < 0.05). On the other hand, being contacted by a doctor, nurse, or other healthcare worker about safe sleep practices were an important factor that influenced safe practices regarding feeding (p < 0.05). Receiving care at a private hospital was associated with safer practices regarding sleeping position and bed-sharing (p < 0.05).

Conclusion

We observed high-risk sleeping practices among Saudi mothers. This includes using soft bedding and unsafe sleeping positions. The importance of this study lies in the future implementation of this result through public health measures aimed at at-risk populations.

Mortality by diseases and medical conditions in the offspring of parents with severe mental illness

PURPOSE

The lifespan of people with severe mental illness (SMI) is shorter compared to the general population. There might be common familial pathway leading to a high co-occurrence of somatic disorders and SMI. To study this we explored the long-term mortality for natural causes in the offspring of people with SMI.

METHODS

Participants were members of the Northern Finland Birth Cohort 1966 (NFBC1966; N = 11,325). The data on cause of deaths of the members were obtained from the Population Register Center until year 2015. The data on hospital-treated psychiatric disorders of parents were obtained from nationwide Care Register for Health Care. Cumulative incidences by age were calculated in the NFBC1966 members having a parent with SMI and those who did not have. We were able to take into account multiple confounders.

RESULTS

Of the total sample of 11,325 offspring, 853 (7.4%) died during the follow-up period, 74 (8.7%) from the study cohort and 779 (91.3%) from the comparison group. These numbers included 160 stillborn children. There were 557 cases of deaths from diseases and medical conditions and 296 deaths from external causes. The adjusted risk ratio for offspring of mothers with SMI was 1.08 (0.72-1.64), and for offspring of fathers with SMI 0.58 (0.36-0.93).

CONCLUSIONS

This was the first long-term follow-up study (up to age 49) of all-cause mortality in offspring of parents with SMI. Our findings were contrary to expectations. Offspring of parents with SMI had no increased risk for dying. In fact, the risk for dying in the group of offspring of fathers with SMI was lower than in the comparison group. This study does not support the assumption of common familial pathway leading to a high co-occurrence of somatic disorders and SMI.

Blood Pressure and Heart Rate Variability in Preschool Children Exposed to Smokeless Tobacco in Fetal Life

Background

Maternal smoking during pregnancy has been associated with higher blood pressure and autonomic imbalance in the offspring. However, it has been difficult to determine the selective prenatal and postnatal contributions as children frequently have been exposed to smoking both before and after birth. The specific role of nicotine is also unclear. We aimed to determine whether exclusive prenatal exposure to nicotine from maternal use of smokeless tobacco (Swedish snus) in pregnancy was associated with blood pressure and autonomic heart rate control in their children.

Methods and Results

We measured oscillometric blood pressures in forty 5‐ to 6‐year‐old children with snus exposure in fetal life (n=21) and in tobacco‐free controls (n=19). Taking the child′s age and height into account, snus‐exposed children had 4.2 (95% CI, 0.2–8.1) mm Hg higher systolic blood pressure than controls (P=0.038). The corresponding sex‐, age‐, and height‐standardized systolic blood pressure centiles were 61 and 46 (95% CI of the difference, 2–28) (P=0.029). Heart rate variability was tested in 30 of the children. The spectral heart rate variability variable low‐frequency/high‐frequency ratio was higher (median, 0.69; interquartile range, 0.45–1.21) in snus‐exposed children than in controls (median, 0.21; interquartile range, 0.32–0.57; P=0.034).

Conclusions

Prenatal snus exposure was associated with higher systolic blood pressure and altered heart rate variability at 6 years of age. These findings may indicate adverse prenatal programming of nicotine, but implications for cardiovascular health in later life remain to be studied. Meanwhile, women should be recommended to abstain from all types of tobacco and nicotine products during pregnancy.

See Editorial Watanabe and Parikh

Updating a Perinatal Risk Scoring System to Predict Infant Mortality

OBJECTIVE

The Birth Score Project (Project WATCH) began in the rural state of West Virginia (WV) in the United States in 1984. The project is intended to identify newborns with a greater risk of infant mortality. The primary objective of this study was to update the current Birth Score based on current literature and rigorous statistical methodology.

STUDY DESIGN

The study merged data from the Birth Score, Birth Certificate (birth years 2008-2013), and Infant Mortality Data (N = 121,640). The merged data were randomly divided into developmental (N = 85,148) and validation (N = 36,492) datasets. Risk scoring system was developed using the weighted multivariate risk score functions and consisted of infant and maternal factors.

RESULTS

The updated score ranged from 0 to 86. Infants with a score of ≥17 were categorized into the high score group (n = 15,387; 18.1%). The odds of infant mortality were 5.6 times higher (95% confidence interval: 4.4, 7.1) among those who had a high score versus low score.

CONCLUSION

The updated score is a better predictor of infant mortality than the current Birth Score. This score has practical relevance for physicians in WV to identify newborns at the greatest risk of infant mortality and refer the infants to primary pediatric services and case management for close follow-up.

A systematic review exploring the relationship between infection and sudden unexpected death between 2000 and 2016: A forensic perspective

Death due to infectious diseases is a major health concern worldwide. This is of particular concern in developing countries where poor-socio economic status and a lack of healthcare resources contribute to the high burden of disease. In some cases death due to infection can be acute and aggressive, and death may occur without a diagnosis whilst the person is still alive. These deaths may ultimately lead to a medico-legal autopsy being performed. There are various mechanisms by which sudden death due to infection may occur. In addition, there are many risk factors associated with sudden death due to infection, which differ between infants and older individuals. However, it is unclear which pathogens and risk factors are most frequently associated with sudden death due to infection. Therefore a systematic review of articles and case reports published between 1 January 2000 and 30 June 2016 was undertaken in order to (1) explore the relationship between pathogens and their causative role and (2) identify the relationship between predisposing and/or risk factors associated with sudden death due to infection. Major databases were searched and after critical appraisal 143 articles were identified. It was found that respiratory infections and deaths involving bacterial pathogens were most commonly associated with these deaths. In addition the most common risk factors in infants were exposure to tobacco smoke and co-sleeping. In adults the most common risk factors were co-morbid conditions and illnesses. This information aids in a better understanding of these deaths and highlights the need for more research in this field, particularly in developing countries.

Antenatal substance misuse and smoking and newborn hypoxic challenge response

OBJECTIVES

Infants of smoking (S) and substance misusing (SM) mothers have an increased risk of sudden infant death syndrome. The aim of this study was to test the hypothesis that infants of SM or S mothers compared with infants of non-SM, non-smoking mothers (controls) would have a poorer ventilatory response to hypoxia, which was particularly marked in the SM infants.

DESIGN

Physiological study.

SETTING

Tertiary perinatal centre.

PATIENTS

21 SM; 21 S and 19 control infants. Infants were assessed before maternity/neonatal unit discharge.

INTERVENTIONS

Maternal and infant urine samples were tested for cotinine, cannabinoids, opiates, amphetamines, methadone, cocaine and benzodiazepines.

MAIN OUTCOME MEASURES

During quiet sleep, the infants were switched from breathing room air to 15% oxygen and changes in minute volume were assessed.

RESULTS

The SM infants had a greater mean increase (p=0.028, p=0.034, respectively) and a greater magnitude of decline (p<0.001, p=0.018, respectively) in minute volume than the S infants and the controls. The rate of decline in minute volume was greater in the SM infants (p=0.008) and the S infants (p=0.011) compared with the controls.

CONCLUSIONS

Antenatal substance misuse and smoking affect the infant's ventilatory response to a hypoxic challenge.

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.

Ventilatory response to hypercarbia in newborns of smoking and substance-misusing mothers

RATIONALE

Infants of mothers who smoked (S) or substance misused (SM) during pregnancy have an increased risk of sudden infant death syndrome (SIDS).

OBJECTIVES

To test the hypothesis that infants of S and SM mothers compared with infants of non-substance-misusing, nonsmoking mothers (control subjects) would have a reduced ventilatory response to hypercarbia and that any reduction would be greater in the SM infants.

METHODS

Infants were assessed before maternity/neonatal unit discharge. Maternal and infant urine samples were obtained and tested for cotinine, cannabinoids, opiates, amphetamines, methadone, cocaine, and benzodiazepines.

MEASUREMENTS AND MAIN RESULTS

Respiratory flow and Vt were measured using a pneumotachograph inserted into a face mask placed over the infant's mouth and nose. The ventilatory responses to three levels of inspired carbon dioxide (0 [baseline], 2, and 4% CO2) were assessed. Twenty-three SM, 34 S, and 22 control infants were assessed. The birth weight of the control subjects was higher than the SM and S infants (P = 0.017). At baseline, SM infants had a higher respiratory rate (P = 0.003) and minute volume (P = 0.007) compared with control subjects and S infants. Both the SM and S infants had a lower ventilatory response to 2% (P < 0.001) and 4% (P < 0.001) CO2 than the control subjects. The ventilatory response to CO2 was lower in the SM infants compared with the S infants (P = 0.009).

CONCLUSIONS

These results are consistent with infants of smoking mothers and substance misuse/smoking mothers having a dampened ventilatory response to hypercarbia, which is particularly marked in the latter group.

Apgar score and the risk of cause-specific infant mortality: a population-based cohort study

BACKGROUND

The Apgar score has been used worldwide as an index of early neonatal condition for more than 60 years. With advances in health-care service provision, neonatal resuscitation, and infant care, its present relevance is unclear. The aim of the study was to establish the strength of the relation between Apgar score at 5 min and the risk of neonatal and infant mortality, subdivided by specific causes.

METHODS

We linked routine discharge and mortality data for all births in Scotland, UK between 1992 and 2010. We restricted our analyses to singleton livebirths, in women aged over 10 years, with a gestational age at delivery between 22 and 44 weeks, and excluded deaths due to congenital anomalies or isoimmunisation. We calculated the relative risks (RRs) of neonatal and infant death of neonates with low (0-3) and intermediate (4-6) Apgar scores at 5 min referent to neonates with normal Apgar score (7-10) using binomial log-linear modelling with adjustment for confounders. Analyses were stratified by gestational age at birth because it was a significant effect modifier. Missing covariate data were imputed.

FINDINGS

Complete data were available for 1,029,207 eligible livebirths. Across all gestational strata, low Apgar score at 5 min was associated with an increased risk of neonatal and infant death. However, the strength of the association (adjusted RR, 95% CI referent to Apgar 7-10) was strongest at term (p<0·0001). A low Apgar (0-3) was associated with an adjusted RR of 359·4 (95% CI 277·3-465·9) for early neonatal death, 30·5 (18·0-51·6) for late neonatal death, and 50·2 (42·8-59·0) for infant death. We noted similar associations of a lower magnitude for intermediate Apgar (4-6). The strongest associations were for deaths attributed to anoxia and low Apgar (0-3) for term infants (RR 961·7, 95% CI 681·3-1357·5) and preterm infants (141·7, 90·1-222·8). No association between Apgar score at 5 min and the risk of sudden infant death syndrome was noted at any gestational age (RR 0·6, 95% CI 0·1-4·6 at term; 1·2, 0·3-4·8 at preterm).

INTERPRETATION

Low Apgar score at 5 min was strongly associated with the risk of neonatal and infant death. Our findings support its continued usefulness in contemporary practice.

FUNDING

None.

High cotinine levels are persistent during the first days of life in newborn second hand smokers

BACKGROUND

Despite the adverse effects of maternal smoking during pregnancy on the newborn's health are well-known, in the pediatric population, a high prevalence exists that is very much affected by second hand smoke (SHS). This study aims to investigate the impact of maternal smoking habits during pregnancy on cotinine levels in newborns during the first days of life. The high association between cotinine concentration in maternal and umbilical cord blood (UCB) has been previously reported, but the levels of blood cotinine that remain in infants born to smokers is unknown.

METHODS

Cotinine concentration was measured in UCB, in maternal and newborn peripheral blood. Data from UCB sample dyads of ninety mothers and from seventy-one newborns were analyzed.

RESULTS

Cotinine levels were significantly different among non-smokers (9.9 ± 5.9 ng/ml), moderate (67.3 ± 7.4 ng/ml), and heavy smokers (137.7 ± 19.5 ng/ml) (p<0.0001). Significant correlations were found between maternal and UCB cotinine (r=0.748; p<0.001), and between UCB and newborn plasma cotinine at 48 h after birth (r=0.541; p<0.001). The smokers exposed their infants to cotinine with a median of 31.7 ± 8.6 ng/ml (moderate) or 59.1 ± 13.3 ng/ml (heavy smokers) until at least, 48 h after birth. Reduced birth weight and length were significantly related with UCB cotinine levels.

CONCLUSIONS

A positive association between UCB and plasmatic cotinine in newborns was found. The high cotinine levels detected in newborns from smoker mothers indicates that their infants are subjected to elevated SHS from birth. These results can help to reinforce the awareness of the adverse effects of smoking during pregnancy.

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.

Ventilatory response to added dead space and position in preterm infants at high risk age for SIDS

OBJECTIVE

The vulnerability of prematurely born infants to sudden infant death syndrome (SIDS) in the prone position might be explained by a reduced ability to respond to a stress, such as hypercarbia, in that position; our objective, therefore, was to further explore the influence of position on the response to a stress.

WORKING HYPOTHESIS

The ability of prematurely born infants to respond to added dead space in the prone compared to the supine position would be impaired at the high risk age for SIDS.

PATIENTS

Twenty infants, median gestational age of 30 (range 24-32) weeks were studied at a median postmenstrual age (PMA) of 45 weeks. In addition, comparisons were made to the results of 25 infants studied at 36 weeks PMA.

METHODOLOGY

Infants were studied supine and prone. Breath by breath minute volume was measured at baseline and after a dead space was incorporated into the breathing circuit; the time constant of the response was calculated. The pressure generated in the first 100 msec of an occlusion (P0.1 ), the maximum inspiratory pressure during an airway occlusion and functional residual capacity (FRC) were also measured in both positions.

RESULTS

The median time constant was longer (38 (range 15-85) vs. 26 (range 2-40) sec (P = 0.002)). P0.1 lower (P = 0.003) and FRC higher (P = 0.031) in the prone compared to the supine position. In the prone position, the time constant correlated with PMA (P = 0.047), that is, the rate of response to added dead space was significantly damped with increasing postnatal age up to the critical age for SIDS.

CONCLUSIONS

The dampened rate of response to added dead space in the prone compared to the supine position lends support to the hypothesis that a poorer response to a stress may contribute to prematurely born infants increased risk of SIDS in the prone position.

Alterations in cholinergic sensitivity of respiratory neurons induced by pre-natal nicotine: a mechanism for respiratory dysfunction in neonatal mice

Nicotine may link cigarette smoking during pregnancy with sudden infant death syndrome (SIDS). Pre-natal nicotine leads to diminished ventilatory responses to hypercarbia and reduced central chemoreception in mice at post-natal days 0-3. We studied how pre-natal nicotine exposure changes the cholinergic contribution to central respiratory chemoreception in neonatal isolated brainstem-spinal cord and slice preparations. Osmotic minipumps, implanted subcutaneously into 5-7 days pregnant mice, delivered saline or nicotine ditartrate 60 mg kg(-1) d(-1) for up to 28 days. In control preparations, acidification of the superfusion medium from pH 7.4 to 7.3 increased the frequency and reduced the amplitude of fictive respiration. In nicotine-exposed neonatal mice, the reduction in amplitude induced by acidification was reduced. In control preparations, atropine suppressed respiratory responses to acidification, while hexamethonium did not. By contrast, in nicotine-exposed preparations, hexamethonium blocked chemosensory responses but atropine did not. Our results indicate that pre-natal nicotine exposure switches cholinergic mechanisms of central chemosensory responses from muscarinic receptors to nicotinic receptors. Modification of the cholinergic contribution to central chemoreception may produce respiratory dysfunctions, as suggested by receptor-binding studies in victims of SIDS.

Effects of alcohol and smoking during pregnancy on infant autonomic control

Prenatal exposure to smoking and alcohol increases the risk for Sudden Infant Death Syndrome (SIDS). Physiological changes associated with these exposures are not well studied. Full-term infants were tested within the first 3 days of life. We hypothesized that maternal alcohol consumption and/or smoking during pregnancy would alter autonomic nervous system function. Newborns whose mothers smoked during pregnancy had lower beat-to-beat heart rate variability in quiet sleep. Infants whose mothers consumed alcohol had lower global heart rate variability, but only in active sleep. Unexposed infants demonstrated increases in heart rate with head-up tilt and decreases in heart rate with head-down tilt, but smoking and alcohol-exposed infants showed no significant responses. These results indicate that autonomic function is altered by prenatal exposure to alcohol and smoking. Such markers may provide early identification of infants at greatest risk for SIDS.

Position and ventilatory response to added dead space in prematurely born infants

OBJECTIVES

Prematurely born infants are at increased risk of sudden infant death syndrome (SIDS) if slept prone.

WORKING HYPOTHESIS

Prematurely born infants would have an impaired response to an added dead space and lower respiratory muscle strength in the prone compared to the supine position.

STUDY DESIGN

Prospective study. PATIENT-SUBJECT SELECTION: Twenty-five infants, median gestational age of 30 (range 26-32) weeks.

METHODOLOGY

The infants were studied supine and prone at a median of 36 weeks postmenstrual age. Breath by breath minute volume was measured at baseline and after a dead space was incorporated into the breathing circuit; the time constant of the response was calculated. The maximum inspiratory occlusion pressure generated (MIOP) and the pressure generated over the first 100 msec (P(0.1)) during airway occlusion were assessed.

RESULTS

The median time constant was longer (26 (range 8-106) sec vs. 22 (range 6-92) sec (P = 0.045)) and the median MIOP (P = 0.001) and P(0.1) (P = 0.003) were lower in the prone compared to the supine position.

CONCLUSION

Prematurely born infants have a dampened response to tube breathing and reduced respiratory muscle strength in the prone compared to the supine position, which may contribute to their increased vulnerability to SIDS in the prone position.

Prenatal to early postnatal nicotine exposure impairs central chemoreception and modifies breathing pattern in mouse neonates: a probable link to sudden infant death syndrome

Nicotine is a neuroteratogen and is the likely link between maternal cigarette smoking during pregnancy and sudden infant death syndrome (SIDS). Osmotic minipumps were implanted in 5-7 d CF1 pregnant mice to deliver nicotine bitartrate (60 mg Kg(-1) day(-1)) or saline (control) solutions for up to 28 d. Prenatal to early postnatal nicotine exposure did not modify the number of newborns per litter or their postnatal growth; however, nicotine-exposed neonates hypoventilated and had reduced responses to hypercarbia (inhalation of air enriched with 10% CO(2) for 20 min) and hypoxia (inhalation of 100% N(2) for 20 s) at postnatal days 0-3 (P0-P3). In contrast, at postnatal day 8, nicotine-exposed neonates were indistinguishable from controls. Isolated brainstem-spinal cord preparations obtained from P0 to P3 nicotine-exposed neonates showed fictive respiration with respiratory cycles longer and more irregular than those of controls, as indicated by high short- and long-term variability in Poincaré plots. In addition, their responses to acidification were reduced, indicating compromise of central chemoreception. Furthermore, the cholinergic contribution to central chemosensory responses switched from muscarinic receptor to nicotinic receptor-based mechanisms. No significant astrogliosis was detectable in the ventral respiratory group of neurons with glial fibrillary acidic protein immunohistochemistry. These results indicate that nicotine exposure affects the respiratory rhythm pattern generator and causes a decline in central chemoreception during early postnatal life. Consequently, breathing would become highly vulnerable, failing to respond to chemosensory demands. Such impairment could be related to the ventilatory abnormalities observed in SIDS.

Maternal tobacco smoking, nicotine replacement and neurobehavioural development

Abstract The adverse effects of prenatal cigarette smoke exposure on human reproductive outcomes are a major scientific and public health concern. In the United States, approximately 25% of women of childbearing age currently smoke cigarettes, and only a small percentage of these individuals quit after learning of their pregnancy. Women interested in smoking cessation during pregnancy have a number of options, including behavioural and pharmacological aids, but nicotine replacement therapy (NRT) is by far the most common approach. While NRT avoids exposure to the myriad compounds present in tobacco smoke, nicotine itself causes damage to the developing nervous system. The purpose of this article is to review the detrimental effects of developmental tobacco smoke exposure on short- and long-term outcomes with particular emphasis on neurobehavioural consequences. In conclusion based on the clear, adverse effects of nicotine on brain development observed in human and animal studies, we suggest that safer alternatives for smoking cessation in pregnancy are badly needed.

Epidemiology of prenatal smoking and perinatal outcomes

During the previous two decades smoking among pregnant women in the developed world declined by about 60-75%. Nevertheless, prenatal smoking remains a common habit and accounts for a significant proportion of fetal morbidity and mortality through both a direct (fetal) and an indirect (placental) effect. The most important smoking-induced placental pathology is placental abruption with reported risk estimates ranging from 1.4 to 4.0. It is almost a consensus that prenatal smoking is a causative factor for placental abruption. Although the evidence is less compelling, smoking mothers are at an increased risk for placenta previa and placenta-previa-accreta combination. There is no association between maternal smoking and the syndrome of idiopathic uterine bleeding. The relationship between maternal smoking and fetal growth is causal, and includes significant reduction in growth of head circumference, abdominal circumference and femur length, with the largest reduction in size observed for femur length. Prenatal smoking is associated with a 20-30% higher likelihood for stillbirth, a 40% elevation in the risk for infant mortality and a 2-fold increase in the incidence of SIDS.

CONCLUSION

Despite a temporal decline in maternal smoking, it still accounts for significant feto-infant morbidity and mortality, and efforts to discourage prenatal smoking need to be intensified.

Alcohol and tobacco consumption among 6-24-months post-partum New Zealand women

Maternal alcohol or tobacco consumption may negatively impact the fetus and breastfeeding infants. Maternal tobacco consumption is also known to negatively affect exposed young children. The current study therefore aimed to assess the prevalence of these lifestyle behaviours in a sample of 6-24-months post-partum women and to elucidate socio-demographic and maternal factors associated with these behaviours. A community-based cross-sectional survey was conducted on 6-24-months post-partum women (n = 318) in three cities in the South Island of New Zealand. Self-reported data on current alcohol and tobacco consumption were collected from these women using a self-administered questionnaire. The results showed that nearly 72% and 23% of these women consumed alcohol and tobacco, respectively. Being Caucasian, having a higher level of education and higher household income were significant factors for alcohol consumption, while being of younger age and of lower educational status were significant factors for tobacco consumption. Pregnancy was associated with lower odds for alcohol consumption (0.07; P < 0.001), but not with lower odds for tobacco consumption. In contrast, breastfeeding was not associated with lower odds of alcohol consumption (0.08; P = 0.075). In conclusion, younger women with lower levels of education and household income must be targeted for public health education on the negative effects of tobacco consumption on their own health and on the health of their children.

Co-sleeping, an ancient practice: issues of the past and present, and possibilities for the future

Co-sleeping-infants sharing the mother's sleep space-has prevailed throughout human evolution, and continued over the centuries of western civilization despite controversy and blame of co-sleeping mothers for the deaths of their infants. By the past century, "crib death" was recognized, later identified as Sudden Infant Death Syndrome (SIDS), and generally found to occur more frequently during bed sharing. Pediatricians warned parents of the dangers of SIDS and other risks of bed sharing, and the frequency of bed sharing decreased markedly over the years. However, during recent decades, bed sharing began to increase, though major issues were raised, including: whether bed sharing actually exacerbates or is protective against the occurrence of SIDS, whether the practice facilitates breast feeding, whether bed sharing is beneficial for an infant's development, and other concerns. Dissention may soon be diminished by use of a crib which opens at the mother's bed-side and is becoming a popular approach to mother-and-infant closeness through the night.

Maternal smoking and sudden infant death syndrome: epidemiological study related to pathology

Various risk factors have been postulated to be related to sudden infant death syndrome (SIDS). Despite its reduction, thanks to the "Back to Sleep" campaign, SIDS is still a major cause of infant mortality in the first year of life. The purpose of this study was to correlate the different risk factors with the autopsy results and thus to determine if one or more of these variables is really specific for SIDS. We collected 128 sudden infant death victims with clinical diagnosis of SIDS and performed a complete autopsy with in-depth histology on serial sections, particularly of the brainstem, in accordance with our necropsy protocol. Histopathologic and immunohistochemical examination of the central autonomic nervous system revealed, in 78 cases of the SIDS group, the following anomalies: hypodevelopment of the arcuate nucleus, somatostatin positive hypoglossus nucleus, tyrosine hydroxylase negativity in the locus coeruleus, gliosis, and hypoplasia of the hypoglossus nucleus. A significant relation was found between maternal smoke and brainstem alterations.

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.

Socio-demographic factors associated with smoking and smoking cessation among 426,344 pregnant women in New South Wales, Australia

Background

This study explores the socio-demographic characteristics of pregnant women who continue to smoke during the pregnancy, and identifies the characteristics of the smokers who were likely to quit smoking during the pregnancy period.

Methods

This was secondary analysis of the New South Wales (NSW) Midwives Data Collection (MDC) 1999–2003, a surveillance system covering all births in NSW public and private hospitals, as well as home births. Bivariate and multiple logistic regression analyses were performed to explore the associations between socio-demographic characteristics and smoking behaviour during pregnancy.

Results

Data from 426,344 pregnant women in NSW showed that 17.0% continued to smoke during pregnancy. The smoking rate was higher among teenage mothers, those with an Aboriginal (indigenous) background, and lower among more affluent and overseas-born mothers. This study also found that unbooked confinements, and lack of antenatal care in the first trimester were strongly associated with increased risk of smoking during pregnancy. About 4.0% of the smoking women reported they may quit smoking during their pregnancy. Findings showed that mothers born overseas, of higher socio-economic status, first time mothers and those who attended antenatal care early showed an increased likelihood of smoking cessation during pregnancy. Those who were heavy smokers were less likely to quit during pregnancy.

Conclusion

Although the prevalence of smoking during pregnancy has been declining, it remains a significant public health concern. Smoking cessation programs should target the population subgroups of women at highest risk of smoking and who are least likely to quit. Effective antismoking interventions could reduce the obstetric and perinatal complications of smoking in pregnancy.

Stable prevalence but changing risk factors for sudden infant death syndrome in child care settings in 2001

OBJECTIVE

A total of 20% of sudden infant death syndrome (SIDS) cases in the 1990s occurred in child care settings. This is much higher than the 8% expected from Census Bureau data. Factors that were associated with child care SIDS included older age; white race; older, more educated mothers; and unaccustomed prone position. Since these findings, much emphasis has been placed on promoting a safe sleep environment in child care. The objectives of this study were to determine the proportion of SIDS occurring in child care in 2001 and to assess risk factors for SIDS in child care.

METHODS

We conducted a retrospective review of all SIDS deaths that occurred in 2001 in 13 US states. Information regarding demographics, SIDS risk factors, and child care arrangements were collected and analyzed. Deaths that occurred in child care were compared with deaths that occurred during parental care.

RESULTS

Of 480 deaths, 79 (16.5%) occurred in child care settings. Of these child care deaths, 36.7% occurred in family child care homes, 17.7% occurred in child care centers, 21.3% occurred in relative care, and 17.7% occurred with a nanny/babysitter at home. Infants in child care were more likely to be older and to die between the hours of 8 am and 4 pm and less likely to be exposed to secondhand smoke. There was no difference in usual, found, or placed sleep position between child care and home deaths. Approximately one half of the infants who died of SIDS in both settings were found prone, and 20% of deaths in both settings were among infants who were unaccustomed to prone sleep.

CONCLUSIONS

The proportion of SIDS deaths in child care has declined slightly but still remains high at 16.5%. Infants in child care are no more likely to be placed or found prone and no more likely to be on an unsafe sleep surface. Educational efforts with child care providers have been effective and should be expanded to unregulated child care providers. In addition, there may be other, yet-unidentified factors in child care that place infants in those settings at higher risk for SIDS.

Developing Rat Lung Has a Sided Pacemaker Region for Morphogenesis-Related Airway Peristalsis

Prenatal airways from diverse species are capable of spontaneous peristaltic contractions in each trimester. The function of this smooth muscle activity is unknown. We demonstrate that peristalsis of the embryonic airway originates from a sided pacemaker focus, is stimulated in a calcium-dependent fashion by the pulmonary morphogen fibroblast growth factor-10 (FGF-10), and appears coupled to lung growth. Airway peristalsis may be crucial for lung development (thereby providing a physiologic role for airway smooth muscle) and play a hitherto unanticipated role in reported transgenic mutant lung phenotypes.

Labor analgesia for the parturient with respiratory disease: what does an obstetrician need to know?

BACKGROUND

Significant alterations occur in the pulmonary system during pregnancy, which primarily serve to meet the increased oxygen consumption by the growing fetus. When pregnancy is complicated by a respiratory tract disorder such as asthma, cystic fibrosis or tobacco-related respiratory complications the peripartum management (both obstetric and anesthetic) may become challenging.

TECHNIQUE

Regional anesthesia remains the technique of choice for these parturients because airway manipulation and endotracheal intubation are avoided.

CONCLUSION

When providing labor analgesia to parturients with asthma, cystic fibrosis, and tobacco-related respiratory disorders every effort should be made to reduce the likelihood of high (thoracic) levels of analgesia and/or anesthesia and subsequent airway compromise.

SIDS prevention--good progress, but now we need to focus on avoiding nicotine

Chong et al. examined risk factors for sudden infant death syndrome (SIDS) before and after the start of the Swedish campaign to reduce the risk of SIDS. They found that maternal smoking was the strongest risk factor for SIDS in the post-campaign compared to the pre-campaign period.

CONCLUSION

After successful results of the SIDS campaigns to prevent prone sleeping, strong efforts need to be undertaken to eliminate maternal smoking during pregnancy altogether without replacing cigarette smoking with other nicotine delivery devices such as snuff, gum or patches.