Introduction

Whether, and in what circumstances, the risk of sudden unexpected death in infancy (SUDI) is increased when an infant shares a sleep surface with another person has been the subject of extensive and vexed debate over the past two decades (1-6). This is largely because of opposing views as to the potential benefits and risks associated with this practice. Researchers remain divided on their stance towards shared sleeping and SUDI. While the United States American Academy of Pediatrics has strongly recommended against sharing a sleep surface with an infant for many years (7-9), a number of researchers in the United Kingdom and Australia question labeling a common sleeping practice a “risk factor” to be advised against. Instead the circumstances, rather than the shared sleeping itself, are recognized as the potential risk (3, 10-12). Whatever one’s personal standpoint, from a clinical perspective, parents are entitled to clear information about the risks and benefits of shared sleeping to enable them to make a well-informed decision concerning the infant care practices they adopt. Health professionals, in both hospital and community settings, play a pivotal role in ensuring that parents are provided with this information, ideally in a non-judgemental manner that is relevant to their specific circumstances.

This chapter commences by defining the important terms used throughout. Second, it examines the prevalence of shared sleeping in both Western and non-Western countries and cultures. Third, it reviews the evidence base concerning the benefits and the risks of sharing a sleep surface with an infant. Fourth, the use of a risk-minimization, as opposed to a risk-elimination, approach in the provision of safe sleeping advice and education is discussed. Finally, the recent move towards devices designed to overcome the risk associated with “direct” shared sleeping, while still maintaining the close mother-infant proximity needed to facilitate breastfeeding, is discussed.

Definitions

Various terms have been used in the literature to define environments in which an infant sleeps in close proximity to a caregiver, including co-sleeping, bed sharing, and room sharing.

Co-sleeping is most commonly defined as a mother and/or her partner (or any other person) being asleep on the same sleep surface as an infant (13-15). However, it was used originally and more broadly to include both room-sharing and bed-sharing practices (7, 9, 12, 16). Variation in definitions frequently creates confusion, particularly since there is evidence that room sharing decreases the risk of SUDI by as much as 50% (7, 17-20), and that it is safer than both sharing a sleep surface (17, 18, 21) and solitary sleeping (when an infant is in a separate room) (18, 20-23).

Bed sharing is frequently used synonymously with co-sleeping (1, 11, 24) to refer to an infant sleeping on the same surface as another person. It has also been defined as bringing an infant onto a surface where sleep is possible, whether intended or not (13, 15, 25). This definition of bed sharing includes instances where the caregiver is awake. The latter, more inclusive definition can be problematic. While there is evidence that sleeping on the same surface as an infant may increase the risk of SUDI under particular conditions (2, 26, 27), there is no evidence that bringing an infant into bed for a short time for feeding or comfort while the caregiver is awake poses any risk (28, 29). In fact, this practice (which would meet the broader definition of bed sharing) is encouraged in postnatal environments which promote skin-to-skin contact as part of Baby Friendly Health Initiatives to support breastfeeding initiation and duration (30, 31).

For clarity, in this chapter the terms sharing a sleep surface and shared sleeping will generally be used in preference to the terms bed sharing and co-sleeping, which will be taken to be synonymous.

Room sharing is defined as the practice of sleeping an infant in their own safe sleeping place in the same room as an adult caregiver. There is consensus among researchers that room sharing between committed caregivers and an infant is protective against SUDI (17, 18, 32) and should be encouraged.

The use of the above defined terminology allows for differentiation of the risks associated with solitary sleeping, room sharing, and environments in which baby and caregiver share the same sleep surface, without creating unnecessary terminological confusion.

Prevalence of Shared Sleeping

Sharing a sleep surface with an infant is a normal and often valued part of infant care in many different cultures. Anthropologists consider it highly probable that infants slept near or on their mother’s body to be fed and nurtured over the course of human evolution, in order to maximize the chances of infant survival and flourishing (33). Today, in most non-Western cultures, mother-infant contact during sleeping remains the norm (34, 35), and it is also commonly practiced in Western societies (36-38).

Shared sleep behavior has been surveyed in many Western countries, including the United States, the United Kingdom, New Zealand, and Australia (9, 36, 39-48), with some studies reporting that the prevalence of shared sleeping has increased over the past two decades (32, 49). In the United States, a large national infant care practice study found that the prevalence of shared sleeping nearly doubled between 1993 and 2010. For the 2001-10 period, 46% of parents reported sharing a sleep surface with their infant (aged less than 9 months) at some point in the previous fortnight, while 13.5% reported usually sleeping with their infant (39). In another national survey, 42% of mothers reported any shared sleeping at 2 weeks of age (40). A third recent study found that almost 60% of mothers reported sharing a sleep surface with their infant at least once (41).

In England, local and national studies show that almost half of all neonates shared a sleep surface with their parents at least once, for all or part of the night (local = 47%, national = 46%), and a fifth of babies slept in the parental bed on a regular basis over the first year of life (42). Similar or higher rates of surface sharing at 3 months of age have been previously reported in other European countries, including Ireland (21%), Germany (23%), Italy (24%), Scotland (25%), Austria (30%), Denmark (39%), and Sweden (65%) (37, 43).

Reports in Australia indicate a population prevalence of sharing a sleep surface of 40-80%, depending on infant age at the time of measurement (45-47, 50, 51). A small study conducted in South Australia demonstrated that 80% of young babies spent some time sharing a sleep surface for at least part of the night (47). A larger Queensland infant care practice study (n=2,534) demonstrated that shared sleeping was common, being the usual practice of 46% of parents when their infants were 3 months of age. Although most infants (51%) were brought into bed for short periods of between one and three hours, almost a third (31%) shared a sleep surface for six hours or more per night (45, 46). More recently a Victorian study surveying 1,126 respondent mothers attending the Maternal and Child Health Service for their infant’s eight-week visit found that 44.7% of participants (n=503) had shared a sleep surface with their infant on at least one occasion since birth (52). Studies of shared sleeping incidence in Western countries, in which sharing a sleep surface is discouraged, may underrepresent the prevalence. Ball and colleagues (53) found that 40% of parents reported where they “intended” their infant to sleep (i.e. a cot), even if the infant had slept in a combination of cot and parental bed.

Recent studies in non-Western countries generally document a greater prevalence of shared sleep arrangements, including Brazil (48%) (54), Thailand (68%) (44), and Malaysia (74%) (55). There are also ethnic and cultural differences within the culturally diverse societies of Western countries, with shared sleeping common among specific subgroups (36). These include breastfeeding mother-infant dyads (36, 47, 56, 57), recent immigrant populations from non-Caucasian countries (36), and indigenous populations (9, 48, 50, 58-60). Shared sleeping is a well-documented characteristic of infant care culture among Māori families in New Zealand (48, 61), with 65% of Māori mothers sharing a sleep surface with their babies for part or all of the night (58). Sharing the same sleep surface is also the usual, often valued, and accepted way for Australian Aboriginal infants and their parents to sleep (62). Studies have found that 68-77% of Aboriginal babies share a sleep surface, with the incidence higher in regional than in metropolitan localities (50, 60). However, as researchers such as Ball and Volpe (36) and Blair (63) observe, since the advantages and risks of shared sleeping are perceived in accordance with the dominant values of any given society, the validity of these subpopulations’ cultural and behavioral differences is rarely recognized in public health safe infant sleep information.

It is clear that shared sleeping prevalence differs according to country and culture, as well as by age at measurement, frequency, and duration. Also differing among countries, communities, and cultures are the demographics of mothers who share a sleep surface, as well as the impact of the shared-sleep environment on the infant. In the United States, shared sleeping is reported to occur more frequently among young, single, poorly educated mothers living in disadvantaged circumstances (36, 64, 65). Conversely, in England, shared sleeping straddles all social classes (37, 42), as it does in Sweden and numerous non-Western cultures, where it is simply perceived as a normal family activity (66). While both the prevalence of shared sleeping and the incidence of SUDI is high in certain cultures, including black (United States), Māori, and Aboriginal populations, other culturally distinct groups such as South Asian families in the United Kingdom (predominantly Bangladeshi and Pakistani) (36, 67-69), Pacific Islanders in New Zealand (70), and Southern Europeans (71), and Thais in Australia (72) have a similarly high incidence of shared sleeping, without a correspondingly higher rate of SUDI. This gives weight to the argument that it is not the shared-sleep environment per se that carries the risk, but the circumstances in which the surface sharing occurs, particularly the presence of other known risk factors for SUDI. These have been shown to be low in those populations with high shared-sleep prevalence but low SUDI incidence (37, 68).

Benefits of Shared Sleeping

Anthropological studies of parent-infant shared sleeping have found sleeping with an infant to be associated with improved settling with reduced crying (73), improved maternal and infant sleep and increased arousals (25, 52, 73-75), increased duration of breastfeeding (38, 39, 76, 77), and reduced formula supplementation (78).

Support for the beneficial effects of shared-sleep environments is also provided in studies of the physiology of mother infant-contact (34, 37). Studies of skin-to-skin contact (kangaroo care) among preterm and newborn infants have documented the benefits of continuous infant-mother contact, including improved cardiorespiratory stability, oxygenation, and thermoregulation (79-81); longer periods of infant sleep and more restful sleep (80, 82, 83); reduced crying (81); and enhanced milk production along with more successful, frequent, and longer duration of breastfeeding (12, 84, 85).

Enhanced maternal-infant bonding, attachment, and maternal responsiveness, particularly when shared sleeping is combined with breastfeeding, have also been associated with shared sleeping in numerous studies (34, 38, 52, 53, 73, 79, 86-92). These studies predominantly measure maternal bonding by mothers’ perceptions of and/or reasons for bed sharing, and by observations of mother-infant interaction during breastfeeding. Mitchell and colleagues’ (93) recent study of shared sleeping and maternal bonding is the first study to attempt to directly test the association between maternal bonding and shared sleeping, using the Postpartum Bonding Questionnaire (PBQ) (94). An inverse relationship between bonding and shared sleeping was reported. However, this study did not control for either maternal depression or postpartum traumatic stress disorder. These conditions have repeatedly been shown to be associated with high scores on the PBQ, and this was acknowledged as a limitation of the research. Mitchell et al. (93) also did not differentiate between planned and reactive shared sleeping. Mileva-Seitz and colleagues (95) contend that the difference between reactive and intentional shared sleeping is crucial for the interpretation of findings. A recent Australian study found that mothers who planned to sleep with their baby viewed their shared sleeping as beneficial for baby, mother, and family, whereas mothers who did not plan to surface share (reactive bed sharers) reported that they did so predominantly out of a desperate need for sleep (52). Ramos and colleagues (96) have also previously shown that intentional shared-sleeping parents are more likely to endorse and be satisfied with shared sleep. Given the study’s finding (93) that shared-sleeping mothers scored more highly on items relating to feelings of anger, irritation, and annoyance towards their infant, differentiating between these groups seems prima facie an important consideration.

Closely related, a study of child attachment security recently found a pattern of greater secure attachment in bed-sharing infants; it also found that infants who had never bed shared at 2 months had greater odds of developing resistant attachment at 14 months (colloquially, becoming a “clingy” child reluctant to separate from their mother) (87). Some caution in interpreting these results should be noted, however, due the absence of a dose response — the “some bed sharing” group demonstrated more secure attachment than the most frequently bed-sharing children. Again, the consideration for maternal and family rationales for bed sharing is important in the interpretation of results.

Another benefit of shared sleep is the long-term positive effect it has into adulthood. Longitudinal studies have suggested that those who shared the parental bed as infants and children become adults with higher self-esteem, and better social skills and emotional outcomes (38, 97, 98).

Risks Associated with Shared Sleeping

Despite the above described benefits, under some circumstances sharing a sleep surface with an infant is strongly associated with SUDI.

Numerous studies have reported a very significantly increased risk of infant death when infants slept with parents who smoke, with odds ratios (OR) generally ranging between 3.9 and 17.7 (11, 18, 21, 24, 27, 28, 70, 119-122). Carpenter’s (18) large case-control study in 20 European regions found the risk of surface sharing was 10-fold greater amongst mothers who smoked. For mothers who did not smoke during pregnancy, the risk associated with shared-sleep environments was very small (OR at 10 weeks 1.56 [95% CI: 0.91-2.68], and only significant during the first eight weeks of life (OR at 2 weeks 2.4 [95% CI: 1.2-4.6]). Vennemann and colleagues’ (27) meta-analysis of 11 published studies on the relationship between shared sleeping and SUDI showed a significant risk for smoking mothers (OR 6.27 [95% CI: 3.94-9.99]). The three papers included in this analysis that reported the risk of shared sleeping among non-smoking parents found the risk to be only slightly, and not significantly, increased (OR 1.66 [95% CI: 0.91-3.01]). More recently, Blair, Sidebotham, Pease, and Fleming’s (24) pooled data from two previous case-control investigations in the United Kingdom found that for infants who slept next to a parent who smoked (but had not consumed alcohol), the risk was four times greater than for those who did not share a sleep surface. A dose-response effect has also been reported when bed sharing, related to whether only the partner smokes, only the mother smokes, or both parents smoke (119).

A more pronounced effect of smoking and shared sleep among younger age groups has been reported in at least two studies (18, 119). In 2004, Carpenter and colleagues (18) demonstrated an interaction with age such that if the mother smoked significant risks were associated with shared sleeping in the first weeks of life (OR at 2 weeks 27.0 [95% CI: 13.3-54.9]). More recently, Carpenter et al. (119) reported that infants who share a sleep surface at 2 weeks of age and whose parents both smoke are at a 65-fold risk of sudden infant death syndrome (SIDS), compared with infants who room shared with non-smoking parents.

There is also evidence of a highly significant interaction between sharing a sleep surface and parental use of alcohol, drugs, or other sedating medication, over and above the risk associated with smoking (11, 21, 119, 121-123). Blair and colleagues (11) report a multivariable odds ratio of 53.26 [95% CI: 4.07-696.96] among SIDS compared to random control infants. When SIDS infants were compared to high-risk controls with similar sociodemographic characteristics the risk, while remaining significant, lowered considerably (OR 11.76 [95% CI: 1.40-99.83]). Subsequent pooled data analyses by the authors have reported a multivariable risk that was 18 times greater when sharing a sleep surface with an adult who had consumed more than two units of alcohol. In Australia, a retrospective case series study examining sleep-related infant deaths from 2008 to 2010 found that alcohol or drug use was present in 70% of infant deaths involving surface sharing (124). As with smoking, the interaction between substances and shared sleep was found to be more pronounced in the younger age groups (aOR at 2 weeks 89.7 [95% CI: 25.3-317.7]) (119).

More generally, studies have documented a risk associated with shared sleeping with younger infants (18, 21, 29, 32, 125) and for infants who were preterm or low birth weight (18, 119, 121). The risk among young infants has been shown to persist even among non-smoking parents (18, 21, 27, 32). Vennemann and colleagues (27) found that the risk of SUDI while bed sharing was 10 times higher among infants aged less than 3 months. Blair et al. (24) and Carpenter et al. (119) both report a fivefold increased risk for infants aged less than 3 months.

Sharing a sofa is also associated with a very high risk of SUDI. A recent meta-analysis (123) found a 23-fold pooled risk for sofa sharing, which is almost eight times the pooled risk for bed sharing. Parental alcohol and drugs use were implicated, in addition to low birth weight, and mechanical suffocation by wedging. In the UK in the SWISS (South West Infant Sleep Scene Study), a sixth of all SUDI occurred when an infant slept on a sofa with a parent (126). For most sofa-sharing deaths, sofa sharing was not the usual practice, and often parents unintentionally fell asleep while settling and feeding their infant (41, 127). Of significant concern, at least a proportion of sofa-sleeping deaths appear to have been an unintended consequence of the advice never to bed share, as parents tried to avoid feeding their infants in the parental bed because they had been told this was a risk (127, 128). A 2010 survey of nearly 5,000 mothers in the United States found that to avoid bed sharing, 55% of mothers fed their infants at night on chairs, recliners, or sofas, and 40% of these admitted to falling asleep with their infants while doing so (41). Similar findings have been reported in the United Kingdom (11, 127).

Studies have reported the risk associated with shared sleeping when coupled with a soft sleep surface, and pillow use (26, 120, 129). Shared sleeping may also increase the risk of overheating rebreathing, airway obstructions, and head covering (7, 9, 130-132), all of which are risk factors for SUDI. Unintentional suffocation is becoming increasingly recognized as a significant contributor to SUDI (26, 133-138). Unsuitable bedding, temporary sleeping arrangements, and a shared sleeping partner have been attributes of accidental suffocation deaths of infants (26, 136, 138). The recognition of the contribution of suffocation at least partially explains findings that the risk of infant death is increased where there are multiple bed sharers (129), alcohol and other substance use (11, 21, 119),¹ and the surface sharer is unusually overtired (18, 122).

The strongest predictor of SUDI has been identified as the combination of recent maternal alcohol consumption and sleeping together with an infant on a soft shared surface (bed or sofa) (11, 119, 123, 127). Cumulatively, the above described findings lead researchers to concur that parents should be strongly advised against sharing a sleep surface when either parent smokes, or has consumed alcohol or drugs, or is sleeping on a couch, sofa, or other inappropriate sleep surface. They should also be made aware that the risks associated with shared sleeping are particularly high if their infant is very young, premature, or of low birth weight, even if they do not smoke (1, 24, 27, 119).

Shared Sleeping Risks in the Absence of Known Hazards

Where researchers cannot reach a consensus is on whether there is a risk associated with shared sleeping in all circumstances. Recently, two individual-level analyses (24, 119) using data from large population-based case-control studies have aimed to quantify whether there is a risk of SUDI associated with shared sleeping in the absence of known hazards, particularly, smoking, alcohol, and other substance use. Both studies concurred that parental smoking, alcohol, and drug use increased the risk of SIDS significantly when shared sleeping was a factor, particularly among the younger age group of infants. However, in the absence of these factors, among older infants different conclusions were reached regarding the risk of bed sharing.

Carpenter and colleagues (119) reported a significantly increased risk of SIDS when shared sleeping occurred in the absence of parental smoking or alcohol consumption for infants aged 3 months or less (aOR = 5.1 [95% CI: 2.3-11.4]). No increased risk was reported among the older age group (aOR = 1.0 [95% CI: 0.3-3.1]). Blair and colleges (24) also found that the risk of bed sharing in the absence of known hazards was elevated among young infants (aged less than 98 days); however, it did not reach significance. However, for infants older than 3 months, bed sharing in the absence of other hazards was significantly protective, with the researchers reporting that the risk halved among this group of infants (OR 0.1 [95% CI: 0.01-0.5] p=0.009). Only one death (0.6%) occurred in an infant older than 3 months of age in the absence of alcohol, smoking, or sofa sharing, compared to 8.5% among controls. Preliminary data from a retrospective study of SUDI in Australia also indicate that the incidence of SUDI involving shared sleeping in the absence of known risk factors is low. Only three of 58 (5%) SUDI involving shared sleeping occurred among infants 3 months of age or older whose mothers neither smoked nor slept on a couch with the infant (139).

Importantly, it is in the conclusions drawn from these statistics, rather than in the findings themselves, that these two groups of researchers differ most significantly. Carpenter and colleagues (119) draw three distinct, yet related, conclusions. First, they conclude that bed-sharing infants aged over 3 months, whose parents do not smoke or consume alcohol or other substances and do not sleep on a sofa, are of very low risk. However, they consider this to be an inconsequentially small group. While it is mentioned both in this study and elsewhere (140), it should be noted that only one UK study (24) has reported on the prevalence of this low-risk bed sharing (8.5%). Noteworthy is that this is still a considerably larger group than some indigenous populations, such as Australian Aboriginals, who constitute 2.4% of the total population. Second, Carpenter et al. (119) conclude that their findings regarding shared-sleeping risk are sufficient to recommend that “professionals and the literature take a more definitive stand against bed-sharing” (p. 10). They further conclude that any negative effect of such a stance on breastfeeding promotion is justified, on the basis that the “costs of bed-sharing ... far outweigh any benefits from increased breast feeding rates” (p. 9).

In contrast, Blair and colleagues determine that despite the findings of these recent studies, the question of whether there is an increased risk of SUDI for an infant routinely sharing a bed with a breastfeeding mother who does not smoke, drink alcohol, or use other recreational or sedating drugs, and who is aware of how to maximize the safety of the sleep environment for the infant remains unclear (1). As such, acknowledging the low risk of this group reported by both studies, they consider that to give blanket advice to all parents never to bed share does not reflect the evidence, particularly given that it has been shown to influence parents to seek alternative, more dangerous sleep surfaces, such as a sofa (24). Third, they consider that, given the considerable evidence of an interdependent, positive relationship between shared sleeping and breastfeeding, the “inherent advantages to the infant need to be considered in addition to the possible risk of SIDS” (24) (p. 6).

The debate, it seems, has never been more polarized. As Ball and Volpe (36) and Cunningham (52) observe, the crux of the problem is that the question of infant sleep location is caught between two competing, and at times contradictory, public health agendas: safeguarding agendas (focused on reducing hazardous sleep environments known to increase infant mortality or adverse events) and wellbeing agendas (those centered around the promotion of breastfeeding, appropriate growth and development, and secure attachment relationships).

Of note, the most recent analysis of the evidence regarding shared-sleep environments (95) determines that conclusive evidence as to the risks of shared sleeping is lacking. However, the researchers assert that this is not due to negative findings, but rather because of a lack of focus on current gaps in knowledge. Consequently, Mileva-Seitz and colleagues (95) call for the end of the single-discipline, pediatrics-dominated approach, arguing that a cross-fertilization within the field is both imperative and long overdue. “It’s time for pediatrics/epidemiology, anthropology/evolutionary psychology and psychiatry/developmental psychology to join forces in a new subfield that we label psychoanthropediatrics” (p. 16).

Delivering the Best Possible Advice: Risk Minimization versus Risk Elimination

The translation of epidemiological findings regarding shared sleeping risk into recommendations and policy for families and health professionals has resulted in two divergent approaches: one focused on risk elimination and the other focused on risk minimization (52, 141).

Proponents of a risk elimination approach seek to reduce the incidence of SUDI by eliminating those risk factors that are considered to be within parents’ control. Adopting a risk elimination standpoint, many public health bodies, most notably the American Academy of Pediatrics, advise parents never to share a sleep surface with their infant (7, 9, 119, 141). At the local level this recommendation has frequently been translated into aggressive anti-shared-sleeping campaigns that have served more to offend and anger than to dissuade parents from sharing a sleep surface with their infant (127). Examples include campaigns featuring bedheads as tombstones, infants sleeping with meat cleavers, and horror “fairy-tales” ending in death.

Irrespective of how aggressive, or otherwise simplistic, the message never to sleep with an infant is, an increasing number of researchers question whether a risk elimination approach is appropriate at all (4, 36, 127, 141-143). First, such recommendations imply that any SUDI that occurs in the context of shared sleeping may be directly attributable to the surface sharing rather than to other risk factors that may be present (127, 141). Moreover, simplistic rhetoric equating safe infant sleep with sleeping alone can obscure the importance of both room sharing and breastfeeding (which is associated with night-time mother-infant proximity) to SUDI reduction (4). As such, it does not accurately reflect the research evidence which, as discussed above, is nuanced and far from straightforward. Second, a risk elimination approach does not take account of research findings that the majority of parents who share a sleep surface do not intend to do so (52, 53). For these parents, surface sharing most frequently occurs under conditions of stress, as they try to sooth an unsettled infant in the context of sleep deprivation (144). Simple advice for parents never to sleep with their infants, a risk elimination approach, is therefore argued to be impractical for new parents. Third, blanket advice against shared-sleep environments has failed to emulate the previous success of infant sleep position advice. This is because the risk elimination approach does not account for the culturally embedded nature of shared sleeping, which results in the recommendations being largely rejected by their target populations (4, 36, 127).

It is increasingly acknowledged that risk minimization polices will be more effective in reducing preventable infant deaths, because risk minimization acknowledges that infants will be placed to sleep, intentionally or unintentionally, in their parent’s bed at some stage, particularly if they are breastfed (12, 34, 52, 88, 141, 145). Advocates of a risk minimization approach contend that in providing safe infant sleep advice, recommendations and policies should consider the documented benefits of shared sleeping, the need to promote and support breastfeeding, the high prevalence and culturally embedded nature of shared sleeping, and the right of parents to make informed choices about their infant’s care (4). Parents should be provided with information that includes benefits, risks, and strategies to reduce the risk and increase safety associated with shared sleep environments, should they decide to, or have no option but to, share a sleep surface with their infant (5, 12, 21, 36, 73, 113, 127, 146). This approach does not prevent providing information about the known dangers of some shared-sleeping practices, nor the circumstances in which it should be avoided altogether (4). Rather, a risk minimization approach simply recognizes that successful interventions to reduce the risk of sleep-related infant death need to address the unique needs and influences of the families they are targeting (4, 36, 85, 141). Parents can then be supported to ensure that they are aware of specific hazardous circumstances and can make informed decisions about sharing a sleep surface with their infant. This risk minimization approach is consistent with, and supported by, recommendations for health professional practice proposed by UNICEF (15, 25, 102, 147), the National Institute for Health and Care Excellence (145), the Australian College of Midwives (148), and Red Nose (formerly SIDS and Kids Australia) (149, 150).

Future Directions

To overcome the risk associated with “direct” shared sleeping, while respecting its social value and importance for initiating and maintain breastfeeding, several devices have been designed to promote safer sleep in close proximity to a parent. These have been termed side-car cots, co-sleepers, safe sleep enablers, and infant safe sleep devices (ISSDs) in the literature (151). There are several sleep enablers available on the market for domestic use, such as the Finnish Baby Box or the Safe and Secure Sleeper, but there has been little formal research into the safety or acceptability of these devices. In addition, these devices may have sides too high to allow physical contact while the infant is contained in the device (e.g. the Baby Box), or they may have design features such as a flexible sleep surface that is reliant on being placed on a firm, flat surface for safe use (e.g. the Safe and Secure Sleeper). Devices to enable “safer” sleep in the context of close contact with a primary caregiver which have been, or are currently being, evaluated are side-car cots, the Change for our Children Pēpi-Pod® Program and First Days Pēpi-Pod® Sleep Space in New Zealand, and the Pēpi-Pod® Program in Australia.

Conclusions

Sharing a sleep surface with an infant is a prevalent parenting practice associated with both positive and negative outcomes. Whether it is beneficial or dangerous depends on a range of factors, including the reasons for, and circumstances in which, shared sleeping occurs, as well as the social and biological connection between the infant and the caregiver. Indeed, so variable is the range of factors associated with shared sleeping and the impact it has on different families that it is inappropriate and possibly harmful to recommend against shared sleeping in any unqualified way, without awareness and consideration of the individual family circumstances, as well as the broader social and cultural context in which it occurs. The proliferation of mixed and oftentimes contradictory infant care messages that have resulted from the polarized debate between advocates and opponents of shared-sleep environments has served only to confuse and alienate families, rather than to educate, empower, and protect them. From a public health perspective, clinicians have a duty of care to provide families with unbiased, accurate, and up-to-date evidence that includes both the benefits and the risks associated with shared-sleep environments, to enable informed decision making. As such, a risk minimization approach is supported. Future research should involve multidisciplinary approaches, and should continue to investigate new and innovative approaches to improve the safety of infant sleep, while recognizing the social and cultural importance of shared-sleep environments to many families. In this regard, the findings of studies involving safe shared-sleep enablers are promising, and may bridge a hitherto longstanding divide.

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Footnotes

1

Suffocation may not explain the interaction between SUDI and drug use in its entirety. Carpenter et al. (119) found that the use of any illegal drugs by the mother increased the risk of death 11-fold and the use of alcohol fivefold, even when room sharing. However, other studies have found no associated risk when the parents did not surface share (11). The precise nature of this interaction remains unexplained, although it is likely also related to social determinants of health that tend to be more prevalent amongst substance-using populations.