Research summaries 2014-2016
Blair, P.S., P. Sidebotham, A. Pease, and P.J. Fleming. 2014. “Bed-Sharing in the Absence of Hazardous Circumstances: Is There a Risk of Sudden Infant Death Syndrome? An Analysis from Two Case-Control Studies Conducted in the UK.” PLOS ONE 9(9): e107799.
This study combines individual-analysis of two population-based case-control studies from five English health regions between 1993 and 1996. This includes 400 SIDS infants and 1,386 controls comparable for age and time of last sleep.
Objective: to assess the risk from bed-sharing when done in the absence of hazardous circumstances to understand its risk relative to other infant sleep locations.
“Hazardous circumstances” was defined as sofa-sharing, alcohol consumption and smoking
This study includes a large epresentative population sample.
This study involves secondary analysis of observational data that are relatively old and the risks posed by different infant sleep locations may have changed over this period. There was a lack of data regarding parental drug consumption, another serious hazard risk when bed-sharing.
Brand, S. et al., 2014. Associations between Infants’ crying, sleep and cortisol secretion and mother’s sleep and well-being. Neuropsychobiology, 69(1), pp.39–51.
Questionnaires were completed by 24 mothers of infants. The infant’s sleep was objectively measured with actigraphs. Saliva samples were taken from infants shortly after waking in the morning. This was repeated after four weeks.
Objective – to investigate the link between cortisol secretion, crying and infant sleep inferred by the relationship with the psychological well-being of the mother and her sleep.
Campbell-Yeo, M.L. et al., 2014. Co-bedding Between Preterm Twins Attenuates Stress Response After Heel Lance: Results of a Randomized Trial. Clinical Journal of Pain, 30(7), pp.598–604.
Randomised control trial of preterm twins. Study is based on premise of several studies that support that intrauterine adaptation of the twins to one another extends to the extrauterine environment having discovered a strong co-regulatory bond between co-bedded infants.
Objective – to see whether co-bedding preterm infants reduces stress response to a common and mildly stressing medical procedure. Previous studies have found mother-infant contact reduces the stress response to heel lance. The authors of this study hypothesised a similar effect with twin-twin contact.
Methods — Infant stress was measured by taking salivary cortisol levels before and after heel lance in both co-bedding and non-bedding preterm twins.
Outcomes — Despite conducting research in a clinically-driven environment the study gathered significant results.
There was a wide variation in infant cortisol levels. Whether infants have identifiable circadian rhythms could be a factor in this, which could influence the results both before and after depending on when the procedure occurs. However the study attempted to collected morning samples only to try to reduce this.
It is difficult or impossible to differentiate pain from stress in infants. Cortisol is released in response to both.
Staff conducting the procedures were unable to be blinded to the study intervention. Potentially this could subconsciously impact their care for different sets of twins. However the similarity in baseline salivary cortisol would suggest otherwise.
Chiu, K. et al., 2014. Are baby hammocks safe for sleeping babies? A randomised controlled trial. Acta paediatrica (Oslo, Norway: 1992), 103(7), pp.783–787.
Randomised control trial of full-term 4-8 week old infants, sleeping in either hammocks (n=14) or standard bassinets (n=9).
Objective – to investigate the safety of hammocks for infant sleep, after two instances of deaths in baby hammocks raised international concern in 2009. There have been concerns surrounding the curve of the hammock causing flexion of the infant’s head, which can compromise the upper airways. Sleep state, oxygen desaturation (and mean haemoglobin oxygen saturation), apnoea and hypopnoea were analysed in both groups.
This study only used a very small sample size of 23 infants. They also only used one type of baby hammock (Natures Sway Baby Hammaock). This does not represent the full range of hammocks. The study only monitored the infants for a short period of time during the day. Future studies could investigate longer periods of nighttime sleep. The study was also conducted at a general practice clinic, which perhaps is not best environment in which to replicate the normal home setting.
Colvin, J.D. et al., 2014. Sleep environment risks for younger and older infants. Pediatrics, 134(2), pp.e406–12.
Cross-sectional study of sleep-related infant deaths between 2004 and 2012.
Objective – to identify multiple elements of a safe sleep environment and their relationship with age. Data was gathered from the National Center for Review and Prevention of Child Deaths (NCRPCD) Case Reporting System database between 2004-2012.
Infants were divided into two groups, younger (0-3 months) and older (4 months to 364 days).
There is a consistent and objective means of classifying a wide range of elements surrounding infant deaths using a standardised data dictionary and data codebook. There was a very large dataset (n=8207) which is beneficial for making more meaningful and generalisable findings.
As in all studies conducted from information gathered from a large database by multiple individuals it is very difficult to be assured of consistent records. The participation in the database is voluntary which could also create bias in the results. It would have been beneficial to also have a control group with which to understand the differences in the prevalence of risk factors in these age groups in infants that have not died. Therefore one could see whether the variation in practices is unique to the infants that have died or is consistent amongst all infants at that age.
McDonnell, E. & Moon, R.Y., 2014. Infant deaths and injuries associated with wearable blankets, swaddle wraps, and swaddling. Journal of Pediatrics, 164(5), pp.1152–1156.
Retrospective review of incidents (n=36) reported to the Consumer Product Safety Commission (CPSC) between 2004 and 2012.
Objective – to understand the risks of swaddling and associated sleep practices.
The source of the data is the Consumer product Safety Commission, which means that all the incidents are the product of self-reporting. This creates bias in the data. There is also uncertainty regarding the brands of swaddling items involved in each case, which could also be illuminating.
Rechtman, L.R., Colvin, J.D., Blair, P.S. and Moon, R.Y. 2014. “Sofas and Infant Mortality.” Pediatrics 134(5): e1293–1300.
Analysis of the data for the 1,024 infant deaths on sofas from 24 states between 2004 and 2012 gathered from the National Center for the Review and Prevention of Child Deaths Case Reporting System database.
As sleeping on sofas poses particular risk of sudden infant death and other sleep-related deaths, this study aims to understand the factors associated with infant deaths on sofas.
The databse used captures a wide-range of important information on child deaths in one place. The database is also expanding to new states, expanding the data range available for analysis, improving data quality. This increases the ability for the database to broaden and identify risk factors for all types of infant deaths.
The system is voluntary, which introduces bias and subjectivity in data reporting. There is also the persistent inconsistency in classifying and coding for accidental suffocation, SIDS, SUDI and unknown or ill-defined cause of death. However this study avoided this pitfall by studying all infant deaths on sofas, lessening the importance of differentiating between these categories. The data regarding the final sleep of SIDS infants were also quite limited, lacking information such socioeconomic status and specific circumstances.
Salm Ward, T.C. 2014. “Reasons for Mother-Infant Bed-Sharing: A Systematic Narrative Synthesis of the Literature and Implications for Future Research.” Maternal and Child Health Journal: 675–90.
Systematic review of 34 international studies between 1990 and 2013
Objective – to understand reasons for mother-infant bed-sharing, including the reasons parents bed-share, the cultural context of bed-sharing and implications of this for interventions and future research.
This is a useful synthesis that could be a good basis for future development and research, and identifies areas for exploration in bed-sharing interventions.
Due to the nature of qualitative data it cannot be replicated, added to another or transferred. Only one author determined eligibility and extracted the data, which could introduce systematic error. This analysis was also unable to determine the quality of the findings related to bed-sharing. In thematic analysis it can be difficult for readers to understand how and at what stage themes were identified. Themes were not stratified by demographic characteristics other than race or ethnicity. It would have been useful to stratify reasons for bed-sharing by other demographic characteristics such as age, educational level or socio-economic status.
Salm Ward, T. C, and Doering, J.J. 2014. “Application of a Socio-Ecological Model to Mother-Infant Bed-Sharing.” Health education & behavior: the official publication of the Society for Public Health Education 41(6): 577–89.
This study reconceptualises 16 studies in the light of the socio-ecological health model.
Objective – to understand variation in bed-sharing between different ethnic or racial groups within a population, given its potential risks, in order to be able to design more successful future public health interventions.
Results were interpreted with a five-level influence socio-ecological model: infant, maternal, family, community and society and the historical context of race.
Tully, K.P. & Ball, H.L., 2014. Maternal accounts of their breast-feeding intent and early challenges after caesarean childbirth. Midwifery, 30(6), pp.712–719.
Study of breastfeeding intention and infant feeding after caesarean section amongst mothers in a postnatal unit in Northeast England between February 2006 and March 2009.
Objective – creastfeeding outcomes are worse after caesarean section compared vaginal birth for both biological factors. This study investigates the reasons and reality of this from the maternal perspective, so as to better understand and improve breastfeeding initiation rates in this important group of mothers. Interviews were conducted with 115 mothers at a postnatal unit on average 1.5 days after caesarean section birth.
The non-leading interview style means that the responses were varied and as unique as possible. The responses are coded in such a way that the study is both qualitative and quantitative.
There is no comparison group of vaginal delivery mothers in the same community. The results of the study may not be generalisable to caesarean section mothers in Baby-Friendly hospitals in which staff are trained to assist maternal breastfeeding successfully.
Volkovich, E. et al., 2015. Sleep patterns of co-sleeping and solitary sleeping infants and mothers: A longitudinal study. Sleep Medicine, 16(11), pp.1305–1312.
Questionnaires, sleep diaries and nighttime actigraphy was conducted amongst 150 healthy married couples expecting their first child (singleton). Parents were recruited during pregnancy and visited during pregnancy, at three and at six months postpartum for monitoring.
Objective – to objectively investigate the “concomitant and predictive relationships’ of mother-infant sleep patterns and arrangements. Of particular interest was the difference in quality and quantity of sleep between co-sleeping and solitary sleeping dyads, whether there is a predictive link associated with maternal sleep pattern and arrangement pre- and post- partum. They also investigated whether there is a bi-directional relationship between infant and maternal sleep at three and six months postpartum and sleeping arrangement.
The sample is of relatively high cultural homogeneity, having been conducted in Israel. This means it is unlikely to be generalisable. Much of the experience of sleep is due to culturally formed expectation, which means that the culture is significant in the reporting of the results. The study recognises that it would have been helpful to evaluate the maternal reasons for co-sleeping. There is also only a small sample of bed-sharers in the sample (n=7) that is unrepresentative of this demographic. They also do not give a means of representing the frequency of co-sleeping, as in most cases it is a continuous measure.
Yoshida et al. 2015. Assessment of nocturnal sleep architecture by actigraphy and one-channel electroencephalography in early infancy. Early Human Development. 91(9):519-526
A Japanese study looking at the characteristics of different sleep patterns in infants by simultaneously using two devices; actigraphy (to monitor movements) and EEG (to measure brain waves). Data was collected whilst babies slept at home.
The study reported results from 27 infants (13 boys and 14 girls) at the same conceptional age of 3-4 months who provided at least 3 days of usable data.
Among the 27 study subjects, there were 14 infants (52%) who were exclusively breastfed. Of the remaining 13 infants, 10 were fed mixture of formula and breastmilk, and 3 were fed formula only.
By combining actigraphy and EEG data the results show that we cannot assume that babies who are quiet all night with little movement are experiencing good quality sleep.
Fifteen infants (56%) were co-sleeping with their parent(s) in the same bed from sleep onset until morning, and 12 of the 14 (86%) exclusively breastfed infants were co-sleeping. Further investigation is needed to ascertain the role of co-sleeping in infant sleep quality.
Due to small participant numbers, the mixed-fed infants and the exclusively formula-fed infants were grouped together. Mothers who mixed-fed their infants were not asked to report the amount of breast or formula milk given, thus the influence of formula milk on sleep may have been overestimated.
Authors discussed the limitations of using portable measuring devices in participants’ homes.
Despite the moderate number of infants involved in the study, the findings showed that the two devices used produced different pictures of what was happening during infant sleep. This highlights the limitations of other studies that rely only on actigraphy or behavioural data to determine infant sleep-wake cycles and sleep quality.
Ball, H.L., Howel, D., Bryant, A., Best, E., Russell and Ward-Platt, M. 2016. “Bed-Sharing by Breastfeeding Mothers: Who Bed-Shares and What Is the Relationship with Breastfeeding Duration?” Acta Paediatrica, 105(6): 628-34.
Randomised breastfeeding trial of 870 mothers, recruited mid-pregnancy. Weekly records were taken of breastfeeding and bed-sharing behaviour for 26 weeks postpartum. Strength of prenatal breastfeeding intent was recorded at recruitment using Likert-type scales.
Objective – to investigate the association between breastfeeding duration and bed-sharing frequency amongst women expressing a prenatal intention to breastfeed.
Only a small proportion of this study identified as an ethnic minority, which could weaken the findings regarding the relationship between non-white ethnicity, bed-sharing and breastfeeding intent. Missing data in this study limited the detail of the analysis the authors hoped to achieve, resulting in an underrepresentation of younger mothers and mothers from lower income households.
Crane, D., and Ball, H.L. 2016. “A Qualitative Study in Parental Perceptions and Understanding of SIDS-Reduction Guidance in a UK Bi-Cultural Urban Community.” BMC pediatrics 16(1): 23.
In-depth narrative interviews conducted with 46 mothers (25 white British origin and 21 Pakistani) of 8-12 week old infants recruited from the pool of participants in the “Born in Bradford” cohort study.
Objective – to understand the differences in implementation of SIDS-reduction guidance to understand the contrasts in SIDS rates and infant care practices between white British and South Asians.
Gradisar et al. 2016. Behavioral Interventions for Infant Sleep Problems: A Randomized Controlled Trial. Pediatrics. 137 (6): e20151486-e20151486.
A study was carried out to evaluate the effects of behavioral interventions on the sleep/wakefulness of infants, parent and infant stress, and later child emotional/behavioral problems, and parent-child attachment.
Significant interactions were found for sleep latency (P < .05), number of awakenings (P < .0001), and wake after sleep onset (P = .01), with large decreases in sleep latency for graduated extinction and bedtime fading groups, and large decreases in number of awakenings and wake after sleep onset for the graduated extinction group.
Salivary cortisol showed small-to-moderate declines in graduated extinction and bedtime fading groups compared with controls. Mothers’ stress showed small-to-moderate decreases for the graduated extinction and bedtime fading conditions over the first month, yet no differences in mood were detected. At the 12-month follow-up, no significant differences were found in emotional and behavioral problems, and no significant differences in secure-insecure attachment styles between groups.
STRENGTHS: Mixed method approach. Follow-up data was gathered at 12 months.
LIMITATIONS: The findings of this study were based on the results from a small participant sample size of only 43 infants who were then randomized into one of the three conditions; graduated extinction (n = 14), bedtime fading (n = 15), or sleep education control (n = 14). A high proportion of infants did not complete the study which decreases the sample size further. Participants were highly educated and well off. Infant sleep location was not considered.
COMMENTS: The initial sample recruitment did not meet the criteria of the power calculation to detect a large effect size, so any significant findings may be false positives, and lack of differences may be false negatives. The results are therefore preliminary and should not be relied on for recommendations.
McKenna, J.J. & Gettler, L.T., 2016. There is no such thing as infant sleep, there is no such thing as breastfeeding, there is only breastsleeping. Acta Paediatrica, International Journal of Paediatrics, 105(1), pp.p.17–21.
This is a commentary article reviewing the information surrounding breastfeeding and infant sleep with an evolutionary perspective.
The authors argue that bed-sharing and breastfeeding as inextricable, the former doubling or tripling the latter. The benefits that increased breastfeeding confers they see as products of developmental adaptation.
They begin by discussing the role attachment by constant contact and co-sleeping plays in lactogenesis and breastfeeding. They believe evolutionarily this is developmentally significant behaviour. With increased breastfeeding through bed-sharing for example there is increased growth in white matter growth and greater cognitive development.
Furthermore they see breastfeeding as significantly more important in human infants than any other due to our immature developmental condition at birth as a result of our large crania and narrow pelvises. They also discuss maternal benefits, including the lower rates of breast cancer amongst breastfeeding mothers.
Thompson, E.L. & Moon, R.Y., 2016. Hazard Patterns Associated With Co-sleepers. Clinical Pediatrics, 55(7), pp.645–649.
Retrospective review of incidents associated with co-sleepers reported to the Consumer Product Safety Commission. This includes 6 deaths and 20 injuries.
Objective – previous studies have investigated the relative safety of co-sleepers (bed-side co-sleepers or in-bed co-sleepers) compared to other means of sleeping, but this study wanted to understand those risks that are associated with them and their hazard patterns.
The data from the Consumer Product Safety Commission in all reported on a voluntary basis by anyone involved in the incident, including emergency or insurance staff, manufacturers or the parents. This could bias the data and is also very anecdotal. It also means that the level of demographic or environmental detail recorded in each case is very variable. The authors recognise that this study is an underrepresentation of the actual prevalence of deaths in co-sleepers, due to the voluntary nature of reporting. There is a small sample size of 26 cases, from which it is difficult to make powerful or meaningful generalisations.