Much has been written about the pros and cons of parent-infant bedsharing, but why parents sleep with their babies has not been the subject of much research. In order to explore this and other aspects of bedsharing, researchers at the Parent-Infant Sleep Lab, Department of Anthropology, University of Durham used a combination of sleep diaries and interviews to study nighttime caregiving in a randomly generated sample of 253 families with newborn infants in the northeast of England. Parents completed a week's worth of structured sleep diaries during their babies' first and third months and were interviewed at the end of both months.
In our analyses, parents and infants were identified as bedsharers if the infant slept in an adult bed with one or both parents for any portion of a night or nights for which the diaries were kept. Subcategories of bedsharing were defined as: habitual bedsharing (infant slept in parental bed all night, every night) combination bedsharing (infant slept in more than one place, but slept in parent's bed for at least part of night on at least two nights per week) occasional bedsharing (infant slept in parent's bed once a week or less) Non-bedsharing families were those in which infants never slept with parents in an adult bed.
We found that parents and infants in the study bedshared regularly. More than half of the babies (54%) bedshared on at least one sleep-diary night during the first month, third month, or both. In interviews, 70 percent of parents reported that they had bedshared with their baby at least once by the time he or she was four months of age. (Figure 1 shows the proportion of habitual, combination, and occasional bedsharing during the infants' first month of life.)
Parents slept with their babies for a variety of reasons, including family-bed ideology (one that encourages children to sleep with their parents whenever they wish), enjoyment of being in close contact, necessity due to lack of space, and anxiety regarding infant health or safety. Among families in our study for whom bedsharing was unrelated to breastfeeding, settling a baby who was having trouble sleeping was a prevalent (55%) reason for bedsharing. In these cases, infrequent bedsharing occurred when a baby who was unhappy at being put to sleep alone protested until the parents, desirous of sleep, allowed him or her into bed.
The most common reason given by parents for bedsharing, however, was the ease and convenience of nighttime breastfeeding. Breastfeeding and bedsharing are closely intertwined, and the existence of a strong and clear relationship between the two is supported by numerous studies.1-8 In the present study, 65 percent of those mothers who had ever breastfed bedshared (at least occasionally), compared to 33 percent of mothers who had never breastfed. For infants who were breastfed for a month or more, the association with bedsharing was even greater: 72 percent of these parents and infants were bedsharers, compared to 38 percent of other babies.
Mothers in the sample who were unprepared for the greater frequency with which breastfed babies wake to feed during the night in comparison with formula-fed babies cited "baby feeding too frequently at night" and "mother needs more sleep" as reasons for giving up breastfeeding in the early weeks. But those who continued breastfeeding, and particularly those who had had experience with previous children, used bedsharing as a means to ameliorate frequent nighttime feeds; many said that, when bedsharing, they barely needed to wake up in order to latch the baby on the breast.
The majority of breastfed babies who slept in their parents' bed were not there all night; most of these parents employed a strategy we call "combination bedsharing," with the baby starting the night alone in a crib or bassinette, being moved into bed at the time of the first breastfeed, and remaining there for the rest of the night.
Several midwives were reported to have taught new mothers, especially mothers who had delivered via c-section, how to breastfeed their infants lying down during their postpartum stay in hospital. Around a third of all mothers who ever breastfed reported that they slept with their infants in their hospital bed. Although at least one researcher cautions against the rare possibility of accidental asphyxia associated with breastfeeding-related bedsharing,9 breastfeeding mothers commonly bedshare as a means to alleviate the sleep disruption of nocturnal breastfeeding--a fact acknowledged in the American Academy of Pediatrics' position statement on bedsharing.10
Because there is a sharp decline in breastfeeding rates between birth and six months in both the UK and the US,11,12 it makes sense to expect that neonates will be more likely to bedshare than older infants. We found that while 47 percent of babies bedshared during their first month, only 29 percent did so during the third month. This relationship between infant age and bedsharing is confirmed by an Australian study that found a significantly greater proportion of younger infants (2 to 12 weeks) than older infants (13 to 24 weeks) bedsharing.13
Approximately 25 percent of formula-fed infants slept with their parents. Around half of these families did so regularly, for ideological reasons, lack of space, or enjoyment; the remainder brought their infants into bed only on rare and specific occasions (e.g., infant illness or irritability, or temporary lack of space, such as when traveling).
The circumstances of irregular or occasional bedsharing are such that safety considerations and potential risk factors might be quite different for these families than for those who practice regular breastfeeding-related bedsharing. In video-observational studies, several researchers have begun to distinguish differences in the bedsharing relationships of mothers and infants who normally sleep together compared with those who do so occasionally. In one study, regularly bedsharing mothers responded to their infants more rapidly than did mothers who did not normally bedshare.14
Other studies found that irregularly bedsharing mothers and non-breastfeeding mothers turned their backs on their infants while bedsharing, while regularly bedsharing, breastfeeding mothers did not.15,16 Mothers who were regular bedsharers slept in closer proximity to their infants than did mothers who did not bedshare regularly.17
In a further study, we videotaped regularly bedsharing parents and infants sleeping together at home, and compared the bedsharing behavior of 10 sets of breast- and formula-feeding mothers and infants. Breastfeeding bedsharers slept together in a characteristic manner that has been independently described by several researchers: The mother spontaneously adopted a distinctive lateral position facing the infant, with her knees drawn up under the infant's feet and her upper arm positioned above the infant's head.18-20 This position facilitates the baby's easy access to its mother's breasts, and babies orient themselves towards their mother's breasts for most of the night. It also provides several safety benefits:
* the baby is flat on the mattress, away from pillows
* the baby is constrained by the mother's knees and arm so that it can't move up or down the bed
* the mother controls the height of bed covers over the baby
* it is very difficult for the baby to be rolled on by either parent, as the mother's elbow and knees are in the way
* the mother is close enough to monitor the baby's temperature and breathing continually.
Bedsharing families who did not breastfeed slept together differently, particularly with respect to the physical orientation to the infant. Mothers who had never breastfed did not curl up around their infants for sleep and did not, therefore, use their own bodies to make a constrained space in the bed for the baby. These mothers primarily positioned their infants at face height in the bed, either between or propped up on the parents' pillows.
Mothers also spent a much smaller proportion of the night facing their infants, and although infants were still oriented towards their mothers for the majority of the night, the mother's position meant there was less face-to-face orientation. It seems that the mothers who didn't breastfeed slept with their infants as if they were sleeping with another adult (faces at same height, no protective sleeping position, less persistent orientation towards infant). As would be expected, feeding frequency and duration differed significantly between breastfeeding and formula-feeding bedsharers; the latter fed on average once per night, while the former fed at least twice and sometimes four or more times in a night. Feeding frequency is related to arousal frequency and arousal synchrony between bedsharing mothers and infants, with breastfeeding mothers and infants experiencing significantly greater arousal frequencies during the night than formula-feeding mothers and infants, together with more synchronous arousals.21
The predominant location in the bed for all infants was in the middle, between both parents. Breastfed infants also spent time sleeping on the outside of the mother, while formula-fed infants tended not to be moved around the bed. The changing location of the breastfed infants reflects the fact that some mothers moved their baby to facilitate feeding from a particular breast. (It was apparent, however, that some mothers were able to feed from either breast while remaining in the same position.)
The other principal difference observed involved infant sleep position. Formula-fed infants predominantly slept supine, while all but one breastfed infant spent the majority of the night in a lateral position, probably because it facilitates breastfeeding. The supine infant sleeping position is now recommended in all Western countries due to the increased risk of cot death among infants sleeping prone.22-30 The lateral sleep position, although recommended in the US until recently, has been discouraged in the UK for almost a decade, as several case-control SIDS studies have indicated that it is associated with a greater risk of SIDS than supine sleep.31-34.
The issue is complicated by the fact that epidemiological studies examining sleeping position have not done so in the context of bedsharing. Several researchers have noted that infants sleeping alone who are positioned laterally may roll forward into the prone position, thereby increasing their risk of SIDS.35-37 An infant sleeping in a lateral position next to its mother, however, would be unable to roll forward. It is currently unknown whether lateral sleeping in this context is also associated with an increased SIDS risk. The relationship between the sleeping position of babies who practice breastfeeding-related bedsharing and SIDS risk is a topic that requires further exploration. The presence of a father in the bed did not present any universal pattern or implications for bedsharing infants. The vast majority of fathers of both breast- and formula-fed infants faced away from their infants for the majority of the night, and their presence did not alter the proximity or orientation of the mother-infant dyad. We did note great individual variation in paternal arousability in response to infants during the night. Clearly, bedsharing is not homogeneous. Parents and infants in the UK bedshare regularly and for a variety of reasons, including convenience, ideology, enjoyment, necessity, and anxiety. The primary reason is ease of nighttime breastfeeding. It should not be assumed, even within an ethnically homogeneous population, that all parents who bedshare with their infants do so in the same way, or for similar reasons. Circumstance and motivation must be considered in assessments of bedsharing safety, and parental reasons for bedsharing must be acknowledged in formulating advice for parents.
1. M. F. Elias et al., "Sleep/Wake Patterns of Breast-Fed Infants in the First Two Years of Life," Pediatrics 77, No.3 (1986): 322-329.
2. R. P. K. Ford et al., "Factors Adversely Associated with Breast Feeding in New Zealand," Journal of Paediatric Child Health 30 (1994): 483-489.
3. E. A. Mitchell et al., "Factors Related to Infant Bedsharing," New Zealand Medical Journal 107 (1994): 466-467.
4. M. S. Clements et al., "Influences on Breastfeeding in Southeast England," Acta Paediatrica 86 (1997): 51-56.
5. H. L. Ball et al., "Where Will the Baby Sleep? Attitudes and Practices of New and Experienced Parents Regarding Cosleeping with Their Newborn Infants," American Anthropologist 10, no. 1 (1999): 143-151.
6. E. Hooker et al., "Sleeping Like a Baby: Attitudes and Experiences of Cosleeping in the Northeast of England," Medical Anthropology 19, no. 3 (2000): 203-222.
7. R. C. H. McCoy et al., "Population-Based Study of Bed Sharing and Breastfeeding,". AAP Conference, Boston, 2000.
8. R. S. Rigda et al., "Bed Sharing Patterns in a Cohort of Australian Infants during the First Six Months after Birth." Journal of Paediatrics and Child Health 36, no. 2 (2000): 117-121.
9. R. Byard, "Is Breast Feeding in Bed Always a Safe Practice?" Journal of Paediatrics and Child Health 34 (1998): 418-419.
10. American Academy of Pediatrics Task Force on Infant Sleep Position and Sudden Infant Death Syndrome, "Changing Concepts on Sudden Infant Death Syndrome: Implications for Infant Sleeping Environment and Sleep Position," Pediatrics 105, no. 3 (2000): 650-656.
11. K. Foster et al., Infant Feeding 1995. London, The Stationery Office, 1995.
12. S. M. Arora et al., "Major Factors Influencing Breastfeeding Rates: Mother's Perception of Father's Attitude and Milk Supply," Pediatrics 106, no. 5 (2000): www.pediatrics.org/cgi/full/106/5/e67 .
13. See Note 8.
14. S. Mosko et al., "Maternal Sleep and Arousals during Bedsharing with Infants," Sleep 20, no. 2 (1997): 142-150.
15. J. Young, "Night-Time Behaviour and Interactions between Mothers and their Infants of Low Risk for SIDS: A Longitudinal Study of Room Sharing and Bedsharing," PhD thesis, Institute of Infant and Child Health, University of Bristol, 1999.
16. H. L. Ball, "Parent-Infant Bed-Sharing Behaviour at Home. Foundation for the Study of Infant Deaths Conference, Cambridge, England, September 12-13, 2001.
17. See Note 15.
18. C. Richard et al., "Sleeping Position, Orientation, and Proximity in Bedsharing Infants and Mothers," Sleep 19, no. 9 (1996): 685-690.
19. See Note 15.
20. See Note 16.
22. E. D. Gibson et al., "Infant Sleep Position Practices Two Years into the 'Back to Sleep' Campaign," Clinical Pediatrics (May 2000): 285-289.
23. A. Esmail et al., "Prevalence of Risk Factors for Sudden Infant Death Syndrome in South East England before the 1991 National 'Back to Sleep' Health Education Campaign," Journal of Public Health Medicine 17, no. 3 (1995): 282-289.
24. T. Dwyer, "Sudden Infant Death Syndrome: After the 'Back to Sleep' Campaign," British Medical Journal 313 (1996): 180-181.
25. S. Beal, "Sudden Infant Death Syndrome in South Australia 1968-97, Part I: Changes over Time," Journal of Paediatrics and Child Health 36, no. 6 (2000): 540-547.
26. See Note 10.
27. R. K. R. Scragg et al., "Infant Room-sharing and Prone Sleep Position in Sudden Infant Death Syndrome," Lancet 347 (1996): 7-12.
28. M. C. Willinger et al., "Factors Associated with Caregivers' Choice of Infant Sleep Position, 1994-1998: The National Infant Sleep Position Study," JAMA 283, no. 16 (2000): 2135-2142.
29. P. J. Fleming et al., "Interaction between Bedding and Sleeping Position in the Sudden Infant Death Syndrome: A Population Based Case-Control Study," British Medical Journal 301 (1990): 85-89.
30. T. Markestad et al., "Sleeping Position and Sudden Infant Death Syndrome (SIDS): Effect of an Intervention Programme to Avoid Prone Sleeping," Acta Paediatrica 84 (1995): 375-378.
31. R. K. R. Scragg and E. A. Mitchell, "Side Sleeping Position and Bed Sharing in the Sudden Infant Death Syndrome," Annals of Medicine 30 (1998): 345-349.
32. P. J. Fleming et al., (2000). "Sudden Infant Death Syndrome: Modifiable Risk Factors and the Window of Vulnerability," in Sleep and Breathing in Children: A Developmental Approach, G. M. Loughlin et al., eds., Marcel Dekker, 2000.
33. B. T. Skadberg et al., "Abandoning Prone Sleeping: Effects on the Risk of Sudden Infant Death Syndrome," Journal of Pediatrics 132, no. 2 (1998): 340-343.
34. R. E. Wigfield et al., "Can the Fall in Avon's Sudden Infant Death Rate be Explained by Changes in Sleeping Position?," British Medical Journal 304 (1992): 282-283.
35. See Note 32.
36. See Note 33.
37. See Note 34.
Helen Ball teaches anthropology and runs the Parent-Infant Sleep Lab at the University of Durham, England. She has been researching parent-infant sleeping arrangements since 1995. She and her research team have two ongoing projects, on co-bedding of twin infants, and bedding-in on the post-natal ward.