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.
To perform a meta-analysis to measure the association between breastfeeding and SIDS.
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.
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).
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.
Comments
SIDS- To be or not to Burp
Hauck's recent meta-analysis (1) only underlines what evolution and common sense have been telling us all the time: breastfeeding is beneficial for infants. Year by year millions of federal and private Dollars are being spent on SIDS research but so far the mystery of the origin of SIDS remains unsolved. Without a single exception, to date all successful measures to reduce SIDS rates were improved methods of infant care and advanced sleep environment conditions. There is no evidence for a conceivable medical SIDS prevention or treatment. None of the successful preventive measures could ever be clearly interpreted and there is no explainable connection between the recommendation of prone position, avoiding thermal stress, eliminating nicotine exposure and soft objects in the infant's sleeping environment, sleeping in the parent's bedroom in an own crib, using a firm matress, breastfeeding and using a pacifier. SIDS turns out to be a phenomenon which can only be contained through optimum infant care.
In the case of proving the influence of feeding practice (breastfeeding versus formula) on the incidence of SIDS there is a historical lack of the self- evident question about postprandial care after the last feeding procedure. The simple missing question is: Was the baby burped properly after feeding/ before sleep?" Nevertheless, after more than a century of progressively concentrated SIDS research, there are no SIDS studies or questionnaires that refer to one of the supposably last measures of infant care before an infant was put to his/her last sleep. Depending on individual baby care advice, on educational, ethnical, sociocultural, emotional and family backgrounds some caregivers evaluate burping a baby to be important, while others don't. In many cases breastfeeding can be seen in connection with socio-economically advantaged conditions, including ample time for infant care. As a matter of fact, there are also poor mothers who frequently burp their babies and socially advantaged mothers who practice formula feeding.
Professional child care centers show a supposed rate of 100% formula feeding and an obvious organizational lack of time to burp all infants properly and repeatedly. The rate of SIDS in those care centers was unproportionally high. Even after educational measures and the acceptance of the supine sleeping position SIDS rates still remained high (2). In addition, yet unidentified factors are suspected in child care that place infants in those settings at higher risk for SIDS (3).
Disadvantageous socio-economic conditions are clearly linked to a higher SIDS rate (4). Caregivers who suffer from a relative lack of environmental support, like some single mothers and mothers with multiple births or twins are more likely to have to attend to many things at the same time. During and after the time-consuming feeding of the infant their attention is likely to be claimed by concurrent challenges, resulting in a lack of time for the infant's thorough burping (5). Mothers who had late or no prenatal care, who consumed alcohol and/or drugs or smoked during pregnancy indicate to be less motivated for perfect infant care and are more likely to loose an infant to SIDS. From a developmental point of view, young mothers should have the healthiest babies, yet an unproportionally high number of their infants dies from SIDS. Teenage mothers, whose babies are rarely a result of family planning, are often distracted from postprandial infant care by other things due to their age related immaturity.
Hypothetically, as well as from a physiological point of view, an eructation of gastric air can amount to SIDS when infants burp during sleep (5). Esophagus and aorta have a distinct anatomical neighborhood, running adjacent in the mediastinum. The aortic arch with its high density of baroreceptors crosses the esophagus, thus creating a main esophageal narrowness. When the esophagus is temporarily bloated by ascending gastric air during sleep, baroreceptors are likely to be stimulated and can create a parasympathetic reaction (falling blood pressure, bradycardia and even cardiac arrest, when the sympathetic alarm system fails to react). After six months of life maturation of cardiorespiratory autonomic control and/or arousal responsiveness should be developed in most infants, when a life threatening trigger hits the sleeping baby. During the first month of life, when only very few SIDS cases occur, the initially small gastric volume may theoretically protect the infant from a relevant trigger, because there is just not enough air to be eructated and to thus activate the baroreflex.
Conclusion: Infant feeding practice (breastfeeding vs. formula feeding) should preferably be seen in close connection with postprandial care, when an epidemiological link with SIDS is created. Varying socioeconomic and educational conditions are likely to have an influence not only on feeding practice, but also on the accuracy of postprandial care. Suspecting unknown infant care factors to be involved into SIDS (3) greater strides must be made in implementing additional infant care recommendations.
Christian Flaig, M.D. Ececutive Emergency Physician, Landeskrankenhaus Bludenz, Austria
References: (1) Hauck FR, Thompson JM, Tanabe KO, Vennemann MM. Breastfeeding and reduced risk of sudden infant death syndrome. Pediatrics 2011; June 13 [Epub ahead of print] (2) Kiechl-Kohlendorfer U, Moon RY. Sudden infant death syndrome (SIDS) and child care centres (CCC).Acta Paediatr. 2008 Jul;97(7):844-5. Epub 2008 May 7 (3) Moon RY, Sprague BM, Patel KM. Stable prevalence but changing risk factors for sudden infant death syndrome in child care settings in 2001. Pediatrics 2005;116:972-7. (4) Blair PS, Sidebotham P, Berry PJ, Evans M, Fleming PJ. Major epidemiological changes in sudden infant death syndrome: a 20-year population-based study in the UK. Lancet. 2006 Jan 28;367(9507):314-9. (5) Flaig C. Inappropriate mediastinal baroreceptor reflex as a possible cause of sudden infant death syndrome - Is thorough burping before sleep protective? Med Hypotheses 2007;68(6):1276-86.
Conflict of Interest:
None declared
Re: Breastfeeding and Reduced Risk of Sudden Infant Death Syndrome: A Meta-analysis
Hauck and colleagues conclude that "breastfeeding is protective against SIDS" and recommend promoting breastfeeding. It is not clear whether they adjusted their results for confounding variables, particularly socioeconomic factors that increase the likelihood of breast- feeding as well as reducing the risk of SIDS. Three well-done multivariable studies2-4 found no protective effect for breastfeeding when confounding factors were considered. (The authors list these unaccountably as univariable studies.) If meta-analysis alone could outweigh good science, a 'large' thymus could still be considered the cause of SIDS, based on 820 publications, and irradiation of the thymus would still be considered protective5. Breast feeding is certainly good, but what about the mothers who have to work to support their family? Is it fair to create anxiety for them by not breastfeeding, and lay a terrible guilt trip on them if their infant dies of SIDS? The evidence for breastfeeding doesn't rise to the level of factors such as back-to-sleep and avoiding thermal stress, cigarette smoke, or bedsharing, all of which are avoidable for the single, uneducated, or impoverished mother. Warren G. Guntheroth, MD Professor of Pediatrics, University of Washington, Seattle
References 1. Hauck FR, Thompson JM, Tanabe KO, Vennemann MM. Breastfeeding and reduced risk of sudden infant death syndrome. Pediatrics 2011; June 13 [Epub ahead of print]. 2. Ponsonby AL, Dwyer T, Kasi SV, Cochrane JA. The Tansmanian SIDS Case- Control Study: univariable and multivariable risk factor analysis. Paediatr Perinat Epidemiol 1995;9:256-72. 3. Fleming PJ, Blair PS, Bacon C, Bensley D, Smith I, Taylor E, Berry J, Golding J, Tripp J. Environment of infants during sleep and risk of the sudden infant death syndrome: results of 1993-5 case-control study for confidential inquiry into stillbirths and deaths in infancy. BMJ. 1996;313:191-5. 4. Mitchell EA. . Mitchell EA, Tuohy PG, Brunt JM, Thompson JM, Clements MS, Stewart AW, Ford RP, Taylor BJ. Risk factors for sudden infant death syndrome following the prevention campaign in New Zealand: a prospective study. Pediatrics. 1997;100:835-40. 5. Guntheroth WG. The thymus, suffocation and sudden infant death syndrome: social agenda or hubris? Perspectives in Biology and Medicine 1993;37:2-13.
Conflict of Interest:
None declared
Safe bedsharing supports exclusive breastfeeding
Dr. Hauck and colleagues' article "Breastfeeding and Reduced Risk of Sudden Infant Death Syndrome: A Meta-analysis" (Pediatrics, June 13 2011) is an important contribution to the data on strategies that reduce infant deaths from SIDS and smothering. However, it is disappointing that Hauck and colleagues apparently believe that "room-sharing without bedsharing" supports exclusive breastfeeding.
Helen Ball's study (Ball, 2003) confirms that mothers quickly discontinue attempts to put the baby back into a crib after breastfeeding. Skin-to-skin contact is central to breastfeeding - without direct skin contact, the baby isn't breastfeeding in the first place. Mothers' prolactin levels that support lactation are highest during bedsharing (Ball, Ward-Platt, Heslop, Leech, & Brown, 2006). Breastfeeding mothers get more sleep when bedsharing (Quillin & Glenn, 2004) and especially when exclusively breastfeeding (Doan, Gardiner, Gay, & Lee, 2007). Lack of sleep is a major factor in postpartum depression. Advising mothers to not bed share with their babies is often discounted, especially by high-risk populations (Chianese, Ploof, Trovato, & Chang, 2009). Even worse, when mothers are warned against bedsharing, they are likely to take their babies to sleep on truly dangerous surfaces - couches and sofas! (Blair, Sidebotham, Berry, Evans, & Fleming, 2006; Fleming, Tsogt, & Blair, 2006; Kendall-Tackett, Cong, & Hale, 2010)
Safe bedsharing and avoidance of pacifiers during early breastfeeding (Howard et al., 2003) supports exclusive breastfeeding. Advice to avoid bedsharing yet exclusively breastfeed for 6 months is unrealistic at best, undermines cultural practices, unfairly burdens mothers for following their own instincts, and ignores the wealth of physiology and biology central to the mother-baby breastfeeding dyad.
Linda J. Smith, BSE, FACCE, IBCLC Bright Future Lactation Resource Centre, Dayton OH
Conflict of Interest:
None declared