Breastfeeding and the risk of sudden infant death syndrome

Selection of a Suitable Animal Model to Evaluate Secretion of Drugs in the Human Milk: A Systematic Approach

Lack of data on drug secretion in human milk is a concern for safe use of drugs during postpartum.Clinical studies are often difficult to perform; despite substantial improvements in computational methodologies such as physiologically based pharmacokinetic modelling, there is limited clinical data to validate such models for many drugs.Various factors that are likely to impact milk to plasma ratio were identified. A literature search was performed to gather available data on milk composition, total volume of milk produced per day, milk pH, haematocrit, and renal blood flow and glomerular filtration rate in various animal models.BLAST nucleotide and protein tools were used to evaluate the similarities between humans and animals in the expression and predominance of selected drug transporters, metabolic enzymes, and blood proteins.A multistep analysis of all the potential variables affecting drug secretion was considered to identify most appropriate animal model. The practicality of using the animal in a lab setting was also considered.Donkeys and goats were identified as the most suitable animals for studying drug secretion in milk.

Outcomes for the apparent life-threatening event infant

Aim

To examine the outcome for apparent life-threatening event infants and the determining factors for that outcome.

Methods

A retrospective review of 903 infants (0-12 months of age) presenting to the pediatric wards at Christchurch Hospital between 1985 and 1996 with events characterized by some combination of apnoea, change in color, and muscle tone. Events, resulting in 1088 admissions, were classified from medical record review according to the severity and underlying conditions, with risk factors and long-term outcomes examined.

Results

The severity of events was reduced with implementing sudden infant death syndrome recommendations regarding the risk of prone sleeping. There were no sudden infant death syndrome deaths on home apnoea monitoring. Five apparent life-threatening event infants, not referred for home apnoea monitoring, subsequently died of sudden infant death syndrome. Two infants died and one suffered significant hypoxic insult when apnoea monitoring was interrupted under the age of 4 months. Asthma and neurodevelopmental conditions appeared to be over-represented subsequently in the apparent life-threatening event group.

Conclusion

Identifying apparent life-threatening event infants at risk of sudden infant death syndrome lacked specificity. The use of apnoea home monitoring appeared protective in this cohort, but safe sleeping practices remained central for reducing sudden infant death syndrome risk.

Early Initiation of Breastfeeding and Its Associated Factors Among Mothers Who Delivered Vaginally in South Gondar Zone Hospitals, Northwest Ethiopia, 2020

Purpose

The early onset of skin-to-skin contact encourages the infant to breastfeed within one hour of birth. The aim of this study was to assess the prevalence of early onset breastfeeding and its associated factors among vaginal delivered mothers in hospitals in the South Gondar Zone of Northwest Ethiopia in 2020.

Methods

From January 12 to February 03, 2020, an institutional-based cross-sectional study was used in South Gondar Zone hospitals. A total of 356 mothers delivered by vaginal were included. Data was collected using a questionnaire administered by the interviewer and entered into version 3.1 of EpiData, and then exported to SPSS version 23.0.0. To classify factors correlated with the outcome variables, logistic regression statistical analyses were used.

Results

In the study area, the prevalence of early breastfeeding initiation among vaginally delivered mothers was 88.2%. Mothers who had unintended pregnancy [adjusted OR=6.00, 95% CI=2.8, 12.5], had professional guidance [adjusted OR=2.75, 95% CI=1.2, 5.6] and experience with breastfeeding [adjusted OR=1.79 95% CI=1.19, 2.68] among vaginal delivered mothers were positively correlated with early breastfeeding initiation.

Conclusion

The type of pregnancy and professional guidance among vaginally delivered mothers were significantly associated with early initiation of breastfeeding. Community-based education and counseling on breastfeeding for pregnant mothers and encouraging all mothers to start early breastfeeding.

Prevalence and associated factors of early initiation of breastfeeding among women delivered via Cesarean section in South Gondar zone hospitals Ethiopia, 2020

Background

Early initiation of breastfeeding is putting the newborn to breast within one hour after birth. This study was aimed to assess prevalence of early initiation of breastfeeding and its associated factors among mothers who delivered by cesarean section in South Gondar Zone hospitals Northwest Ethiopia, 2020.

Methods

An institutional based cross-sectional study was employed in South Gondar Zone hospitals from June 12 to July 03, 2020. A total of 356 cesarean delivered mothers were included. Data were collected using interviewer administered questionnaire and entered in to Epi Data version 4.2 and then exported to SPSS version 23.0. Logistic regression statistical analyses were used to identify factors associated with the outcome variables.

Results

The prevalence of early initiation of breastfeeding among mothers who delivered by cesarean section was 51.9%. Mothers who had intended pregnancy [AOR = 2.69, 95% CI (1.34–5.38)], had professional guidance [AOR = 2.68, 95% CI (1.18–6.10)], had breastfeeding experience [AOR = 2.25, 95% CI (1.35–3.75)], and had four and above antenatal care visits [AOR = 2.20, 95% CI (1.24–3.91)] were positively associated with early initiation of breastfeeding among mothers who delivered by cesarean section.

Conclusion

Type of pregnancy, professional guidance, had four or more antenatal care and breastfeeding experience were significantly associated with early initiation of breast feeding among mothers who delivered by cesarean section. Community based breastfeeding education and counseling to pregnant mothers and encouraging all mothers to follow recommended ANC visit is should be recommended.

A Review of the Factors Associated With the Timely Initiation of Breastfeeding and Exclusive Breastfeeding in the Middle East

Background:

Breastfeeding supplies all the nutrients that infants need for their healthy development. Breastfeeding practice is multifactorial, and numerous variables influence mothers’ decisions and ability to breastfeed. This review identifies the factors potentially affecting the timely initiation of breastfeeding within an hour after birth and exclusive breastfeeding in the first 6 months in Middle Eastern countries.

Methods:

The Medline, ScienceDirect, and Web of Science databases were keyword-searched for primary studies meeting the following inclusion criteria: (1) publication in the English language between January 2001 and May 2017, (2) original research articles reporting primary data on the factors influencing the timely initiation of breastfeeding and/or exclusive breastfeeding, (3) the use of World Health Organization definitions, and (4) Middle Eastern research contexts. A random effect model was used to establish the average prevalence of the timely initiation of breastfeeding and exclusive breastfeeding in the Middle East.

Results:

The review identified 19 studies conducted in Saudi Arabia (7), Iran (3), Egypt (2), Turkey (2), Kuwait (1), the United Arab Emirates (1), Qatar (1), Lebanon (1), and Syria (1). The meta-analysis established that 34.3% (confidence interval [CI]: 20.2%-51.9%) of Middle Eastern newborns received breastfeeding initiated within an hour of birth, and only 20.5% (CI: 14.5%-28.2%) were fed only breast milk for the first 6 months. The 8 studies exploring breastfeeding initiation most commonly associated it with the following: delivery mode, maternal employment, rooming-in, and prelacteal feeding. The 17 studies investigating exclusive breastfeeding most frequently linked it to the following: maternal age, maternal education, maternal employment, and delivery mode.

Conclusions:

Middle Eastern health care organizations should fully understand all the determinants of breastfeeding identified by this review to provide suitable practical guidance and advice to help new mothers to overcome barriers where possible and to contribute to improving infant and maternal health in the region.

Both Prenatal and Postnatal Interventions Are Needed to Improve Breastfeeding Outcomes in a Low-Income Population

BACKGROUND

Breastfeeding provides many health benefits for mothers and their infants that span their life course. Despite this, national breastfeeding rates are below benchmarks set by the CDC (Centers for Disease Control and Prevention). Breastfeeding rates in the Detroit low-income population are particularly low.

OBJECTIVE

To measure the effect of hospital-based prenatal and postnatal breastfeeding interventions on breastfeeding initiation and continuation rates in a low-income population. The interventions implemented were a prenatal breastfeeding education curriculum and a hospital-based breastfeeding support group.

METHODS

A total of 650 women were tracked via chart review and telephone survey after delivery to assess breastfeeding initiation, continuation, and goal achievement. The baseline group (n = 330) received care in the hospital-associated prenatal clinic before intervention implementation; the postintervention group (n = 320) received breastfeeding education and had a hospital-based breastfeeding support group made available to them, in which some participated. Data were analyzed using the chi-squared test and the Student's t-test.

RESULTS

Breastfeeding initiation rates were greater in the postintervention group (p < 0.0001). The breastfeeding continuation rate at or beyond 6 months did not differ among baseline and postintervention groups (p = 0.5), but was greater among women who also participated in the breastfeeding support group compared with women who participated in the prenatal intervention alone. Participation in interventions did not affect the rate, at which women reported meeting their breastfeeding goals.

CONCLUSION

Both prenatal education and ongoing postdischarge support are needed to improve breastfeeding continuation.

Breastfeeding and dummy use have a protective effect on sudden infant death syndrome

We conducted a literature review on the effect of breastfeeding and dummy (pacifier) use on sudden infant death syndrome (SIDS). From 4343 abstracts, we identified 35 relevant studies on breastfeeding and SIDS, 27 on dummy use and SIDS and 59 on dummy use versus breastfeeding.

Conclusion

We found ample evidence that both breastfeeding and dummy use reduce the risk of SIDS. There has been a general reluctance to endorse dummy use in case it has a detrimental effect of breastfeeding. However, recent evidence suggests that dummy use might not be as harmful to breastfeeding as previously believed.

Factors influencing breastfeeding exclusivity during the first 6 months of life in developing countries: a quantitative and qualitative systematic review

Breastfeeding is the most advantageous feeding option for infants, and epidemiological studies provide evidence for its promotion. The objective of this review was to comprehensively delineate the barriers and facilitators of exclusive breastfeeding of infants aged 0-6 months old by mothers in developing countries. A search of CINAHL, MEDLINE and PsycINFO was carried out to retrieve studies from January 2001 to January 2014. Using our inclusion criteria, we selected studies that described barriers and facilitators of exclusive breastfeeding. Qualitative and quantitative studies were considered. Twenty-five studies involving 11 025 participants from 19 countries were included. Barriers and facilitators of exclusive/full breastfeeding were identified, analysed tabulated and summarised in this review. Maternal employment was the most frequently cited barrier to exclusive breastfeeding. Maternal perceptions of insufficient breast milk supply was pervasive among studies while medical barriers related to illness of mothers and/or infants as well as breast problems, rather than health care providers. Socio-cultural factors such as maternal and significant other's beliefs about infant nutrition also often constitute strong barriers to exclusive breastfeeding. Despite these barriers, mothers in developing countries often possess certain personal characteristics and develop strategic plans to enhance their success at breastfeeding. Health care providers should be informed about the determinants of exclusive breastfeeding and provide practical anticipatory guidance targeted at overcoming these barriers. In so doing, health care providers in developing countries can contribute to improving maternal and child health outcomes.

Scientific consensus forum to review the evidence underpinning the recommendations of the Australian SIDS and Kids Safe Sleeping Health Promotion Programme--October 2010

This paper summarises a 1-day scientific consensus forum that reviewed the evidence underpinning the Australian SIDS and Kids Safe Sleeping Health Promotion Programme. The focus was on each of the potentially modifiable risk factors for sudden unexpected deaths in infancy, including sudden infant death syndrome (SIDS) and fatal sleeping accidents. In particular infant sleeping position, covering of the face, exposure to cigarette smoke, room sharing, unsafe sleeping environments, bed sharing, immunisation, breastfeeding, pacifier use and Indigenous issues were discussed in depth. The participants recommended that future 'Reducing the Risk' campaign messages should focus on back to sleep, face uncovered, avoidance of cigarette smoke before and after birth, safe sleeping environment, room sharing and sleeping baby in own cot.

Family medicine obstetrics: pregnancy and nutrition

This article discusses pregnancy and nutrition in 3 main timeframes, the prepregnancy nutritional health evaluation, nutrition during pregnancy, and nutrition during the puerperium, and also includes comments on nutrition and lactation. This article begins with a brief review of the risks of obesity (increased body mass index [BMI]) and anorexia (decreased BMI), with special attention to these undesired conditions during pregnancy, followed by a section on nutrients other than calories. Information on body weight, minerals, and vitamins during pregnancy is reviewed. This article ends with information on nutrition in the postpartum period.

Antagonism of progesterone receptor suppresses carotid body responses to hypoxia and nicotine in rat pups

We tested the hypothesis that antagonism of progesterone receptor (PR) in newborn rats alters carotid body and respiratory responses to hypoxia and nicotinic receptor agonists. Rats were treated with the PR antagonist mifepristone (daily oral gavage 40 μg/g/d) or vehicle between postnatal days 3 and 15. In 11-14-day-old rats, we used in vitro carotid body/carotid sinus nerve preparation and whole body plethysmography to assess the carotid body and ventilatory responses to hypoxia (65 mmHg in vitro, 10% O2 in vivo) and to nicotinic receptor agonists (as an excitatory modulator of carotid body activity-nicotine 100 μM for in vitro studies, and epibatidine 5 μg/kg, i.p., which mainly acts on peripheral nicotinic receptors, for in vivo studies). The carotid body responses to hypoxia and nicotine were drastically reduced by mifepristone. Compared with vehicle, mifepristone-treated rats had a reduced body weight. The ventilatory response to epibatidine was attenuated; however, the hypoxic ventilatory response was similar between vehicle and mifepristone-treated pups. Immunohistochemical staining revealed that mifepristone treatment did not change carotid body morphology. We conclude that PR activity is a critical factor ensuring proper carotid body function in newborn rats.

SIDS and other sleep-related infant deaths: expansion of recommendations for a safe infant sleeping environment

Despite a major decrease in the incidence of sudden infant death syndrome (SIDS) since the American Academy of Pediatrics (AAP) released its recommendation in 1992 that infants be placed for sleep in a nonprone position, this decline has plateaued in recent years. Concurrently, other causes of sudden unexpected infant death occurring during sleep (sleep-related deaths), including suffocation, asphyxia, and entrapment, and ill-defined or unspecified causes of death have increased in incidence, particularly since the AAP published its last statement on SIDS in 2005. It has become increasingly important to address these other causes of sleep-related infant death. Many of the modifiable and nonmodifiable risk factors for SIDS and suffocation are strikingly similar. The AAP, therefore, is expanding its recommendations from being only SIDS-focused to focusing on a safe sleep environment that can reduce the risk of all sleep-related infant deaths including SIDS. The recommendations described in this report include supine positioning, use of a firm sleep surface, breastfeeding, room-sharing without bed-sharing, routine immunization, consideration of a pacifier, and avoidance of soft bedding, overheating, and exposure to tobacco smoke, alcohol, and illicit drugs. The rationale for these recommendations is discussed in detail in this technical report. The recommendations are published in the accompanying "Policy Statement--Sudden Infant Death Syndrome and Other Sleep-Related Infant Deaths: Expansion of Recommendations for a Safe Infant Sleeping Environment," which is included in this issue (www.pediatrics.org/cgi/doi/10.1542/peds.2011-2220).

Breastfeeding and reduced risk of sudden infant death syndrome: a meta-analysis

CONTEXT

Benefits of breastfeeding include lower risk of postneonatal mortality. However, it is unclear whether breastfeeding specifically lowers sudden infant death syndrome (SIDS) risk, because study results have been conflicting.

OBJECTIVE

To perform a meta-analysis to measure the association between breastfeeding and SIDS.

METHODS

We identified 288 studies with data on breastfeeding and SIDS through a Medline search (1966-2009), review articles, and meta-analyses. Twenty-four original case-control studies were identified that provided data on the relationship between breastfeeding and SIDS risk. Two teams of 2 reviewers evaluated study quality according to preset criteria; 6 studies were excluded, which resulted in 18 studies for analysis. Univariable and multivariable odds ratios were extracted. A summary odds ratio (SOR) was calculated for the odds ratios by using the fixed-effect and random-effect inverse-variance methods of meta-analysis. The Breslow-Day test for heterogeneity was performed.

RESULTS

For infants who received any amount of breast milk for any duration, the univariable SOR was 0.40 (95% confidence interval [CI]: 0.35-0.44), and the multivariable SOR was 0.55 (95% CI: 0.44-0.69). For any breastfeeding at 2 months of age or older, the univariable SOR was 0.38 (95% CI: 0.27-0.54). The univariable SOR for exclusive breastfeeding of any duration was 0.27 (95% CI: 0.24-0.31).

CONCLUSIONS

Breastfeeding is protective against SIDS, and this effect is stronger when breastfeeding is exclusive. The recommendation to breastfeed infants should be included with other SIDS risk-reduction messages to both reduce the risk of SIDS and promote breastfeeding for its many other infant and maternal health benefits.

SIDS: past, present and future

Despite the large reduction in SIDS mortality, which occurred in the early 1990s following the 'Back to Sleep' campaigns, SIDS remains the leading cause of death in the postneonatal age group. This paper describes the position in the 1980s, the contribution of the New Zealand Cot Death Study, what should be recommended and the current research priorities.

CONCLUSION

SIDS is preventable. Application of what we currently know could eliminate SIDS. The challenge is to find ways of implementing our knowledge.

Bed-sharing at 3 months and breast-feeding at 1 year in southern Brazil

OBJECTIVE

To investigate the association between bedsharing at age 3 months and breastfeeding (BF) at age 12 months.

STUDY DESIGN

Almost all children born in Pelotas, Brazil in 2004 (99.2%) were enrolled in a cohort study. At birth, age 3 months, and age 12 months, mothers were interviewed to gather information on sociodemographic, reproductive, BF, and bedsharing characteristics. Bedsharing was defined as habitual sharing of a bed between mother and child for the entire night or part of the night. The analysis was limited to children from single births who were breastfed at 3 months. Multivariate analyses were carried out using Poisson regression.

RESULTS

Of 4231 live births, 2889 were breastfed at age 3 months. The prevalence of BF at age 12 months was 59.2% in the children who bedshared at 3 months and 44% in those who did not (adjusted prevalence ratio [PR] for weaning= 0.75; 95% confidence interval [CI] = 0.69-0.81; P < .001). Among children who were exclusively breastfed at 3 months, 75.1% of those who also bedshared were still breastfed at age 12 months, versus 52.3% of those who did not bedshare (adjusted PR = 0.63; 95% CI = 0.53- 0.75; P < .001). The adjusted PR was 0.74 (95% CI = 0.60-0.90; P = .003) in children who were predominantly breastfed and 0.83 (95% CI = 0.76-0.90; P < .001) in those who were partially breastfed.

CONCLUSIONS

Bedsharing at 3 months protected against weaning up to age 12 months.

Health professional knowledge of breastfeeding: are the health risks of infant formula feeding accurately conveyed by the titles and abstracts of journal articles?

Effective promotion of breastfeeding is constrained if health professionals' knowledge on its importance is deficient. This study asks whether formula feeding is named as the risk factor in published research or whether it is considered the unspoken norm. A systematic analysis is conducted of the information content of titles and abstracts of 78 studies that report poorer health among formula-fed infants. This shows a surprising silence in the studies examined; formula is rarely named in publication titles or abstracts as an exposure increasing health risk. In 30% of cases, titles imply misleadingly that breastfeeding raises health risk. Only 11% of abstracts identify formula feeding as a health risk exposure. Initiatives to increase breastfeeding have described the importance of accurate language and well-informed health professional support. If widespread, this skew in communication of research findings may reduce health professionals' knowledge and support for breastfeeding.

Mother-infant cosleeping, breastfeeding and sudden infant death syndrome: what biological anthropology has discovered about normal infant sleep and pediatric sleep medicine

Twenty years ago a new area of inquiry was launched when anthropologists proposed that an evolutionary perspective on infancy could contribute to our understanding of unexplained infant deaths. Here we review two decades of research examining parent-infant sleep practices and the variability of maternal and infant sleep physiology and behavior in social and solitary sleeping environments. The results challenge clinical wisdom regarding "normal" infant sleep, and over the past two decades the perspective of evolutionary pediatrics has challenged the supremacy of pediatric sleep medicine in defining what are appropriate sleep environments and behaviors for healthy human infants. In this review, we employ a biocultural approach that integrates diverse lines of evidence in order to illustrate the limitations of pediatric sleep medicine in adopting a view of infants that prioritizes recent western social values over the human infant's biological heritage. We review what is known regarding infant sleeping arrangements among nonhuman primates and briefly explore the possible paleoecological context within which early human sleep patterns and parent-infant sleeping arrangements might have evolved. The first challenges made by anthropologists to the pediatric and SIDS research communities are traced, and two decades of studies into the behavior and physiology of mothers and infants sleeping together are presented up to the present. Laboratory, hospital and home studies are used to assess the biological functions of shared mother-infant sleep, especially with regard to breastfeeding promotion and SIDS reduction. Finally, we encourage other anthropologists to participate in pediatric sleep research using the unique skills and insights anthropological data provide. By employing comparative, evolutionary and cross-cultural perspectives an anthropological approach stimulates new research insights that influence the traditional medical paradigm and help to make it more inclusive. That this review will potentially stimulate similar research by other anthropologists is one obvious goal. That this article might do so makes it ever more possible that anthropologically inspired work on infant sleep will ultimately lead to infant sleep scientists, pediatricians, and parents becoming more informed about the consequences of caring for human infants in ways that are not congruent with their evolutionary biology.

Sudden infant death syndrome

Despite declines in prevalence during the past two decades, sudden infant death syndrome (SIDS) continues to be the leading cause of death for infants aged between 1 month and 1 year in developed countries. Behavioural risk factors identified in epidemiological studies include prone and side positions for infant sleep, smoke exposure, soft bedding and sleep surfaces, and overheating. Evidence also suggests that pacifier use at sleep time and room sharing without bed sharing are associated with decreased risk of SIDS. Although the cause of SIDS is unknown, immature cardiorespiratory autonomic control and failure of arousal responsiveness from sleep are important factors. Gene polymorphisms relating to serotonin transport and autonomic nervous system development might make affected infants more vulnerable to SIDS. Campaigns for risk reduction have helped to reduce SIDS incidence by 50-90%. However, to reduce the incidence even further, greater strides must be made in reducing prenatal smoke exposure and implementing other recommended infant care practices. Continued research is needed to identify the pathophysiological basis of SIDS.

Predictors of preterm infant feeding methods and perceived insufficient milk supply at week 12 postpartum

As part of a large, nonexperimental, prospective, longitudinal study, 94 pump-dependent mothers of a nonnursing preterm infant were queried via telephone at weeks 8 to 12 post-partum about their infant feeding method. At week 12, 44.6% provided own mother's milk, 26.6% provided own mother's milk + artificial milk, and 28.7% provided artificial milk only. Logistic regression analyses identified the following predictors for risk of artificial milk at week 12 postpartum: multiple birth, week 6 inadequate milk supply, maternal age younger than 29 years, and intended length of lactation less than 34 weeks. Predictors for risk of maternal perceived insufficient milk supply for weeks 8 to 12 postpartum included week 6 inadequate milk supply, unemployment, and infant hospital discharge after postpartum day 42. Further research is needed to assist pump-dependent mothers of preterm infants with sustaining their milk supply.

Recommendations for sudden infant death syndrome prevention: a discussion document

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

The cost of infant feeding in Liverpool, England

Objective:

To investigate feeding practices in infants under the age of 4 months in Liverpool, England with particular reference to the cost of infant feeding.

Design:

A cross–sectional survey consisting of self–completion questionnaires and interviews.

Setting:

Subjects' homes within Central and South Liverpool Primary Care Trust areas.

Subjects:

One hundred and forty–nine women (aged 18 to 43 years) and their infants (mean age 13 weeks).

Results:

The average weekly cost of breast–feeding was £11.58 compared with £9.60 for formula–feeding. Many breast– and formula–feeding women spent money however on items that were not needed or used only once or twice. This was especially true of first–time mothers. Characteristics significantly associated with higher spending were: feeding method – mothers that had or were partially breast–feeding (P=0.001), education – those educated to degree level (P=0.028), socio–economic status – those in social classes I and II (P=0.002) and age – those aged 30 years and over (P=0.003).

Conclusions:

This study demonstrates that while breast–feeding is often promoted as being free, this is not the case. Better information needs to be given to parents to avoid wasting money on items that are unnecessary, or where cheaper alternatives are available.

Inappropriate mediastinal baroreceptor reflex as a possible cause of sudden infant death syndrome – Is thorough burping before sleep protective?

Despite extensive research, a link between the assumed mechanisms of death and known risk factors for sudden infant death syndrome (SIDS) has not yet been established. Modifiable risk factors such as prone sleeping position, nicotine exposure and thermal stress and non-avoidable risk factors like male gender and some risky socio-economic conditions could be detected, but the etiology of SIDS remains unknown. In many SIDS cases histopathological findings suggest an involvement of vital autonomic control functions and unidentified trigger factors seem to play a role. From a hypothetical point of view, a developmental sympatheticovagal imbalance of the cardiovascular reflex control could cause a predisposition for SIDS. An assumed gastroesophageal trigger impulse is possibly developed during the first weeks of life and could lead to the infant's vagal reflex death. Air swallowed during feeding escapes through the esophagus while the infant is sleeping. The temporarily bloated esophagus exerts pressure on neighboring mediastinal baroreceptors, which is potentially misinterpreted as a rise in arterial pressure. The following cardiodepressoric baroreceptor reflex could lead to arterial hypotension, bradycardia and cardiac arrest. Sleeping in prone position may create an increased thoracic pressure on mediastinal baroreceptors, causing a more pronounced vagal reflex and an increased likelihood of SIDS. Prone position in connection with soft objects in the infant's sleeping environment potentially generates an increased oculobulbar pressure, resulting in an additional cardiodepressoric condition (Aschner-Dagnini phenomenon). From the sixth month of life onwards the sympatheticovagal balance seems to have matured sufficiently to compensate the life-threatening challenges in most infants. Insufficient postprandial burping could either create another independent modifiable risk factor or present the missing link to a common trigger mechanism for SIDS. Further investigations may possibly lead to the explicit recommendation to burp all infants sufficiently and repeatedly before sleep.

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.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

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

CONCLUSION

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

The changing concept of sudden infant death syndrome: diagnostic coding shifts, controversies regarding the sleeping environment, and new variables to consider in reducing risk

There has been a major decrease in the incidence of sudden infant death syndrome (SIDS) since the American Academy of Pediatrics (AAP) released its recommendation in 1992 that infants be placed down for sleep in a nonprone position. Although the SIDS rate continues to fall, some of the recent decrease of the last several years may be a result of coding shifts to other causes of unexpected infant deaths. Since the AAP published its last statement on SIDS in 2000, several issues have become relevant, including the significant risk of side sleeping position; the AAP no longer recognizes side sleeping as a reasonable alternative to fully supine sleeping. The AAP also stresses the need to avoid redundant soft bedding and soft objects in the infant's sleeping environment, the hazards of adults sleeping with an infant in the same bed, the SIDS risk reduction associated with having infants sleep in the same room as adults and with using pacifiers at the time of sleep, the importance of educating secondary caregivers and neonatology practitioners on the importance of "back to sleep," and strategies to reduce the incidence of positional plagiocephaly associated with supine positioning. This statement reviews the evidence associated with these and other SIDS-related issues and proposes new recommendations for further reducing SIDS risk.

Modifiable risk factors for SIDS in Germany: results of GeSID

BACKGROUND

The incidence of sudden infant death syndrome (SIDS) has been falling in Germany over the last decade. However, little is known about the prevalence and the importance of well-known risk factors in Germany since a local prevention campaign in 1992.

DESIGN

A 3-y, population-based, case-control study was conducted in half of Germany, consisting of 333 cases. All sudden and unexpected deaths in infancy, if they fitted the inclusion criteria, were included in the study. Parental interview was carried out soon after the death, and three living control infants, matched for age, gender, region and sleep time, were recruited.

RESULTS

The prevalence of placing infants prone to sleep was only 4% in the control group, but this was associated with a markedly increased risk of SIDS (adjusted odds ration, aOR=6.08). Other modifiable risk factors for SIDS were: maternal smoking during pregnancy, breastfeeding for less than 2 wk (aOR=1.71) and co-sleeping (aOR=2.71), while using a pacifier during the last sleep reduced the risk (aOR=0.39).

CONCLUSIONS

Previously recognized risk factors for SIDS also occur in Germany. Despite knowledge about the major modifiable risk factors for SIDS, these factors are still present in Germany. To reduce the incidence of SIDS in Germany, a continued effort is needed to inform all parents about preventable risk factors for SIDS.

Increasing breastfeeding rates in New York City, 1980-2000

Our objective was to determine temporal patterns of breastfeeding among women delivering infants in New York City (NYC) and compare national breastfeeding trends. All hospitals in NYC with obstetric units were contacted in May and June 2000 to provide information on the method of infant feeding during the mother's admission for delivery. Feeding was categorized as "exclusive breastfeeding," "breast and formula," or "exclusive formula." The first two categories were further grouped into "any breastfeeding" in the analysis. Hospitals were classified as "public" and "private," and patients were classified by insurance type as "service" and "private." Data between public and private hospitals and service and private patients were compared. Breast-feeding trends over time were compared by using previous iterations of the same survey. Of 16,932 newborns, representing approximately 80.0% of all reported live births in the city during the study period, 5,305 (31.3%) were exclusively breastfed, 6,189 (36.6%) were fed a combination of breast milk and formula, and the remaining 5,438 (32.1%) were exclusively formula-fed. Infants born in private hospitals were 1.6 times more likely to be exclusively breastfed compared with infants discharged from public hospitals (33% vs. 21%, respectively). Similarly, private patients were more likely than service patients to exclusively breastfeed their infants (39.6% vs. 22.9%, respectively) and to use a combination of breast and formula (i.e., any breastfeeding) (73.6% vs. 62.0%, respectively). From 1980 to 2000, the proportion of exclusive breastfeeding increased from 25.0% to 31.0%, the percentage of combined feeding increased from 8.0% to 37.0%, and the percentage of any breastfeeding increased from 33.0% to 68.0%. NYC has more than doubled the rate of breastfeeding since 1980. However, there is much progress to be made, and continued efforts are vital to maintain current gains in breastfeeding, improve the rates further, and prolong the duration of breastfeeding.

Breastfeeding and the use of human milk

Considerable advances have occurred in recent years in the scientific knowledge of the benefits of breastfeeding, the mechanisms underlying these benefits, and in the clinical management of breastfeeding. This policy statement on breastfeeding replaces the 1997 policy statement of the American Academy of Pediatrics and reflects this newer knowledge and the supporting publications. The benefits of breastfeeding for the infant, the mother, and the community are summarized, and recommendations to guide the pediatrician and other health care professionals in assisting mothers in the initiation and maintenance of breastfeeding for healthy term infants and high-risk infants are presented. The policy statement delineates various ways in which pediatricians can promote, protect, and support breastfeeding not only in their individual practices but also in the hospital, medical school, community, and nation.

Pathogenesis of early atherosclerotic lesions in infants

High serologic lipid levels, infections, and genetic susceptibility have been proposed as possible etiologic factors of initial atherosclerotic lesions of the coronary arteries in infancy. At a recent WHO annual meeting, it was stated that breast milk substitutes cause irreparable damage in infants. This prompted us to verify whether formula feeding and parental cigarette smoking might play a role in the pathogenesis of early atherosclerotic alterations in infancy. The major epicardial coronary arteries from 36 infants dying suddenly and unexpectedly (sudden infant death syndrome) were embedded in paraffin and serially cut for histologic examination. In 67% of the cases, multifocal coronary early atherosclerotic lesions of varying entities were detected. The alterations ranged from focal plaques with mild myointimal thickening to juvenile soft plaques reducing the arterial lumen. A significant correlation was observed between the early atherosclerotic lesions and the risk factors considered. In particular, we noted different morphologic patterns related to formula feeding and cigarette smoking. Baby formula feeding and parental cigarette smoking might have an atherogenic effect on the coronary walls as from the first months of life. The lesions appear to be larger and more diffuse when both these atherogenic factors are present.

A controlled study of the relationship between Bordetella pertussis infections and sudden unexpected deaths among German infants

OBJECTIVE

This was a prospective, controlled, multicenter study to investigate the relationship between Bordetella pertussis infections and sudden unexpected deaths among German infants.

DESIGN

Between 1995 and 1997, all infants who died at 7 to 365 days of age and for whom autopsies were performed in 1 of 8 participating institutes of legal medicine were enrolled. During a standardized autopsy, nasopharyngeal specimens (NPSs) and tracheal specimens were obtained for polymerase chain reaction (PCR) assays to detect B pertussis. The oligonucleotide primers PTp1 and PTp2, which specifically amplify a 191-base pair DNA fragment of the pertussis toxin operon of B pertussis, were used. Two control subjects (matched according to residence, age, gender, and nationality) were enrolled for each case subject, via a network of pediatricians in private practice, and NPSs were obtained from those infants. Parents of case subjects and control subjects were asked to provide specific information on respiratory illnesses of the child, contact with a known case of pertussis, or close contact with a person with a cough illness during the 4 weeks before death or enrollment, as well as the child's pertussis immunization status. The pathologists performing the autopsies were unaware of the PCR results.

RESULTS

Enrolled were 254 infants (66% male) with sudden unexpected deaths and 441 matched control subjects. Autopsies according to protocol were performed for 234 of the case subjects (92%); a diagnosis of sudden infant death syndrome (SIDS) was made for 76%. For the remaining subjects, causes of death were respiratory or other infections (14%), congenital anomalies or organ failures (4%), aspiration (2%), or accidents or traumatic events (4%). PCR results were positive for B pertussis for 12 case subjects (5.1%) (all with SIDS or respiratory infections) and 5.3% of control subjects. Of the 12 case subjects with positive PCR results, 10 (83%) were male. Questionnaires had been returned by the parents of 5 of the 12 infants. Three had experienced a respiratory illness (all with cough), beginning 7, 14, and 19 days before death. None had a known contact with a case of pertussis. Four of 15 control infants (27%) with positive PCR findings for B pertussis had a cough illness, indicating possible pertussis, and 2 of those 4 developed typical symptoms (whooping). Background information was received from 116 parents (46%) of case subjects and from parents of all control subjects. Upper respiratory tract infections within 4 weeks before death were reported for 53% of case subjects and 38% of control subjects. Also, fewer case subjects (33%) than control subjects (68%) had received age-adequate numbers of pertussis vaccine doses.

CONCLUSIONS

The concept of infection as a factor in SIDS is supported by a number of observations, including the seasonal distribution of the occurrence of SIDS; the high incidence of concurrent upper respiratory tract infections among infants dying as a result of SIDS; the peak age at 3 to 4 months; nicotine use in a child's household, which predisposes children to respiratory infections such as otitis media; and the protective role of breastfeeding. A prominent role might be suspected for B pertussis, for several reasons. 1) B pertussis infections in infancy are frequently associated with apneic spells, which are occasionally life-threatening and, if leading to death, might be reported as SIDS. 2) Epidemiologic evidence from the United Kingdom, Sweden, and Norway indicates that SIDS is associated with B pertussis infection. 3) In a previously published study, we detected B pertussis DNA in the nasopharynx of 9 of 51 consecutive infants (18%) with sudden unexpected deaths. This is the first prospective, controlled study to investigate the possible etiologic role of B pertussis in SIDS. Clinically unrecognized B pertussis infections were relatively frequent (5.3%) among control infants during the course of our study. The rate of infection was similar or perhaps greater for control subjects, compared with case subjects (1.7%), when only NPS results were compared. This may seem surprising but is supported by other studies, in which asymptomatic infections or mild respiratory illnesses were observed among infants exposed to B pertussis. Careful autopsies, including histologic evaluations of organ specimens and use of PCR to detect B pertussis in NPSs and tracheal specimens, represented a strength of this study. Our general findings were as expected. The majority of cases were classified as SIDS. The second largest group included infants for whom respiratory infections were found. The findings of various other diagnoses, which in several instances would have been undiscovered otherwise, emphasize the need for autopsies after unexpected infant deaths. What is the significance of the identified B pertussis infections in 12 cases? Several pieces of evidence support the plausibility of a cause-and-effect relationship. Eight of the 12 case subjects died before 6 months of age, the typical age for death attributable to pertussis. In autopsies, 9 of the subjects were found to have signs of respiratory infections; for 2 infants, the autopsies suggested that death was attributable to a respiratory infection. One additional infant (data not shown) had brain edema (which could have been attributable to hypoxemia during pertussis). Lower rates of completed primary series or age-adequate numbers of pertussis vaccine doses among case subjects than among control subjects may indicate that immunization against pertussis protects children from death attributable to unrecognized B pertussis infection. Moreover, a recent study indicated that immunization with diphtheria-tetanus-pertussis vaccine induces antibodies that cross-react with pyrogenic staphylococcal toxins, which have been implicated in several cases of SIDS. Other microorganisms may be involved in the sudden death of infants, as suggested in this study by the higher rate of a history of concurrent upper respiratory tract infections among case subjects, compared with control subjects. Similarly, in a Scandinavian study, 48% of 244 SIDS case subjects, compared with 31% of 869 control subjects, exhibited symptoms of upper airway infection during the last week before death or interview, respectively. Because SIDS is a diagnosis of exclusion, every attempt should be made to identify a cause of death during autopsy. This should include the search for pathogenic microorganisms in the respiratory tract with the use of PCR and other sensitive tests. In conclusion, B pertussis infection was found for 12 of 234 infants (5.1%) with unexpected deaths, and the infections might have contributed to the deaths.

Frequency of bed sharing and its relationship to breastfeeding

Bed sharing has been promoted as facilitating breastfeeding but also may increase risks for sudden, unexpected infant deaths. This prospective cohort study was performed to determine the prevalence of adult and infant bed sharing and its association with maternal and infant characteristics. Demographic data were collected from 10,355 infant-mother pairs at birth hospitals in Eastern Massachusetts and Northwest Ohio, and follow-up data were collected at 1, 3, and 6 months by questionnaire. Associations with bed sharing were estimated using odds ratios and 95% confidence intervals from multiple logistic regression models while adjusting for confounding variables. At 1, 3, and 6 months, 22%, 14%, and 13% of infant-mother pairs shared a bed, respectively. On multivariate analysis, race/ethnicity and breastfeeding seemed to have the strongest association with bed sharing. These factors need to be considered in any comprehensive risk to benefit analysis of bed sharing.

Breastfeeding advice given to African American and white women by physicians and WIC counselors

OBJECTIVE

This study determined rates of breastfeeding advice given to African American and white women by medical providers and WIC nutrition counselors, and sought to determine whether racial differences in advice contributed to racial differences in rates of breastfeeding.

METHODS

The study used data from the 1988 National Maternal and Infant Health Survey, a cross-sectional survey of a nationally representative sample of mothers with a live birth, infant death, or fetal death in 1988. The authors compared white women (n=3,966) and African American women (n=4,791) with a live birth in 1988 on self-reported rates of medical provider and WIC advice to breastfeed, WIC advice to bottlefeed, and breastfeeding.

RESULTS

Self-reported racial identification did not predict medical provider advice. However, being African American was associated with less likelihood of breastfeeding advice and greater likelihood of bottlefeeding advice from WIC nutrition counselors. In multivariate analyses controlling for differences in advice, being African American was independently associated with lower breastfeeding rates (odds ratio [OR] = 0.41, 95% CI 0.32, 0.52).

CONCLUSIONS

African American women were less likely than white women to report having received breastfeeding advice from WIC counselors and more likely to report having received bottlefeeding advice from WIC counselors. However, African American and white women were equally likely to report having received breastfeeding advice from medical providers. Lower rates of breastfeeding advice from medical or nutritional professionals do not account for lower rates of breastfeeding among African American women.

Sudden infant death syndrome and social deprivation: assessing epidemiological factors after post-matching for deprivation

As part of the confidential enquiry into stillbirths and deaths in infancy (CESDI), a 3-year population-based case-control study was specifically designed to look at risk factors associated with sudden infant death syndrome (SIDS) after the dramatic fall in incidence. The study was conducted between 1993 and 1996 in five English Health Regions (population 17 million) with parental interviews for each death and four age-matched controls. The aim of this analysis was to investigate the extent to which epidemiological characteristics associated with SIDS were particular to the syndrome or more general markers for socio-economic deprivation. One control was reassigned to each case post-matched for infant age, time of sleep and socio-economic status using components of the Townsend Deprivation Score. The post-matched analysis involved 323 SIDS infants and 323 controls with a similar socio-economic profile. Notable factors significant in the original univariable analysis that became non-significant after post-matching included young maternal age (median: 23 years 4 months SIDS vs. 23 years 11 months post-matched controls), being an unsupported mother (13.6% SIDS vs. 11.1% post-matched controls) and being bottle-fed (56.7% SIDS vs. 55.4% post-matched controls). Other factors, although clearly related to deprivation, such as parental smoking, remained significant in both the univariable and multivariable post-matched analyses.

Breastfeeding advice given to African American and white women by physicians and WIC counselors

OBJECTIVE

This study determined rates of breastfeeding advice given to African American and white women by medical providers and WIC nutrition counselors, and sought to determine whether racial differences in advice contributed to racial differences in rates of breastfeeding.

METHODS

The study used data from the 1988 National Maternal and Infant Health Survey, a cross-sectional survey of a nationally representative sample of mothers with a live birth, infant death, or fetal death in 1988. The authors compared white women (n=3,966) and African American women (n=4,791) with a live birth in 1988 on self-reported rates of medical provider and WIC advice to breastfeed, WIC advice to bottlefeed, and breastfeeding.

RESULTS

Self-reported racial identification did not predict medical provider advice. However, being African American was associated with less likelihood of breastfeeding advice and greater likelihood of bottlefeeding advice from WIC nutrition counselors. In multivariate analyses controlling for differences in advice, being African American was independently associated with lower breastfeeding rates (odds ratio [OR] = 0.41, 95% CI 0.32, 0.52).

CONCLUSIONS

African American women were less likely than white women to report having received breastfeeding advice from WIC counselors and more likely to report having received bottlefeeding advice from WIC counselors. However, African American and white women were equally likely to report having received breastfeeding advice from medical providers. Lower rates of breastfeeding advice from medical or nutritional professionals do not account for lower rates of breastfeeding among African American women.

Facilitating the use of evidence in practice: evaluating and adapting clinical practice guidelines for local use by health care organizations

This article describes a framework for evaluating and adapting existing practice guidelines for local use by health care organizations and groups. The framework presents the major issues related to guideline adaptation and breaks them down into manageable steps. Many steps of the framework are illustrated using the process used by the Registered Nurses Association of Ontario to develop best practice guidelines for breastfeeding.

Breast feeding and the sudden infant death syndrome in Scandinavia, 1992-95

AIMS

To assess the effects of breast feeding habits on sudden infant death syndrome (SIDS).

METHODS

The analyses are based on data from the Nordic Epidemiological SIDS Study, a case-control study in which parents of SIDS victims in the Scandinavian countries between 1 September 1992 and 31 August 1995 were invited to participate, each with parents of four matched controls. The odds ratios presented were computed by conditional logistic regression analysis.

RESULTS

After adjustment for smoking during pregnancy, paternal employment, sleeping position, and age of the infant, the adjusted odds ratio (95% CI) was 5.1 (2.3 to 11.2) if the infant was exclusively breast fed for less than four weeks, 3.7 (1.6 to 8.4) for 4-7 weeks, 1.6 (0.7 to 3.6) for 8-11 weeks, and 2.8 (1.2 to 6.8) for 12-15 weeks, with exclusive breast feeding over 16 weeks as the reference. Mixed feeding in the first week post partum did not increase the risk.

CONCLUSIONS

The study is supportive of a weak relation between breast feeding and SIDS reduction.

A review of the anatomy of the upper airway in early infancy and its possible relevance to SIDS

BACKGROUND

Since the danger of prone sleeping in the first 6 months of life has been publicised, there has been a dramatic and consistent reduction in the incidence of sudden infant death syndrome (SIDS). However, unexpected infant deaths and apparent life-threatening events (ALTEs) continue to occur that are clearly not associated with known epidemiological risk factors.

AIMS

To review the unique features of the anatomy and function of the upper airway of the young infant which contribute to increased vulnerability to hypoxia in this age group. We discuss the clinical identification of those infants at risk of obstruction or restriction of the upper airway and the management of the 'at risk' infant.

CONCLUSIONS

In the era after the "back to sleep" campaigns, it is likely that an increasing proportion of cases of ALTEs and SIDS will be related to obstruction or limitation of upper airway size leading to sleep hypoxia/asphyxia. This type of problem may be anticipated by evaluation and investigation of infants with signs or a clinical history consistent with possible upper respiratory tract compromise, including micrognathia.

Optimal duration of exclusive breastfeeding

BACKGROUND

: Although the health benefits of breastfeeding are widely acknowledged, opinions and recommendations are strongly divided on the optimal duration of exclusive breastfeeding. Much of the debate has centered on the so-called 'weanling's dilemma' in developing countries: the choice between the known protective effect of exclusive breastfeeding against infectious morbidity and the (theoretical) insufficiency of breast milk alone to satisfy the infant's energy and micronutrient requirements beyond four months of age. The debate over whether to recommend exclusive breastfeeding for four to six months versus 'about six months' has recently become heated and acrimonious.

OBJECTIVES

: The primary objective of this review was to assess the effects on child health, growth, and development, and on maternal health, of exclusive breastfeeding for six months versus exclusive breastfeeding for three to four months with mixed breastfeeding (introduction of complementary liquid or solid foods with continued breastfeeding) thereafter through six months. A secondary objective was to assess the child and maternal health effects of prolonged (greater than six months) exclusive breastfeeding versus exclusive breastfeeding for six months followed by mixed breastfeeding thereafter.

SEARCH STRATEGY

: Two independent literature searches were carried out, together comprising the following databases: MEDLINE (as of 1966), Index Medicus (prior to 1966), CINAHL, HealthSTAR, BIOSIS, CAB Abstracts, EMBASE-Medicine, EMBASE-Psychology, Econlit, Index Medicus for the WHO Eastern Mediterranean Region, African Index Medicus, Lilacs (Latin American and Caribbean literature), EBM Reviews-Best Evidence, the Cochrane Database of Systematic Reviews (The Cochrane Library Issue 3, 2000), and the Cochrane Controlled Trials Register (The Cochrane Library Issue 3, 2000). No language restrictions were imposed. The two searches yielded a total of 2,668 unique citations. Contacts with experts in the field yielded additional published and unpublished studies.

SELECTION CRITERIA

: We selected all internally-controlled clinical trials and observational studies comparing child or maternal health outcomes with exclusive breastfeeding for six or more months versus exclusive breastfeeding for at least three to four months with continued mixed breastfeeding until at least six months. Studies were stratified according to study design (controlled trials versus observational studies), provenance (developing versus developed countries), and timing of compared feeding groups (three to seven months versus later).

DATA COLLECTION AND ANALYSIS

: Two reviewers independently assessed study quality (using a priori assessment criteria) and extracted data.

MAIN RESULTS

: Twenty independent studies meeting the selection criteria were identified by the literature search: nine from developing countries (two of which were controlled trials in Honduras) and 11 from developed countries (all observational studies). The two trials did not receive high methodologic quality ratings but were nonetheless superior to any of the observational studies included in this review. The observational studies were of variable quality; in addition, their nonexperimental designs were not able to exclude potential sources of confounding and selection bias. Definitions of exclusive breastfeeding varied considerably across studies. Neither the trials nor the observational studies suggest that infants who continue to be exclusively breastfed for six months show deficits in weight or length gain, although larger sample sizes would be required to rule out modest differences in risk of undernutrition. The data are conflicting with respect to iron status, but at least in developing country settings where newborn iron stores may be suboptimal, suggest that exclusive breastfeeding without iron supplementation through six months may compromise hematologic status. Based primarily on an observational analysis of a large randomized trial in Belarus, infants who continue exclusive breastfeeding for six months or more appear to have a significantly reduced risk of one or more episodes of gastrointestinal infection. No significant reduction in risk of atopic eczema, asthma, or other atopic outcomes has been demonstrated in studies from Finland, Australia, and Belarus. Data from the two Honduran trials suggest that exclusive breastfeeding through six months is associated with delayed resumption of menses and more rapid postpartum weight loss in the mother.

REVIEWER'S CONCLUSIONS

: We found no objective evidence of a 'weanling's dilemma'. Infants who are exclusively breastfed for six months experience less morbidity from gastrointestinal infection than those who are mixed breastfed as of three or four months, and no deficits have been demonstrated in growth among infants from either developing or developed countries who are exclusively breastfed for six months or longer. Moreover, the mothers of such infants have more prolonged lactational amenorrhea. Although infants should still be managed individually so that insufficient growth or other adverse outcomes are not ignored and appropriate interventions are provided, the available evidence demonstrates no apparent risks in recommending, as a general policy, exclusive breastfeeding for the first six months of life in both developing and developed country settings. Large randomized trials are recommended in both types of setting to rule out small effects on growth and to confirm the reported health benefits of exclusive breastfeeding for six months or beyond.