BACKGROUND. In the last 20 years, the prevention campaigns to reduce the risk of sudden infant death syndrome were very successful. In some countries the advice to breastfeed is included in the campaigns' messages, but in other countries it is not.
OBJECTIVE. To examine the association between type of infant feeding and sudden infant death syndrome.
METHODS. The German Study of Sudden Infant Death is a case-control study of 333 infants who died of sudden infant death syndrome and 998 age-matched controls.
RESULTS. A total of 49.6% of cases and 82.9% of controls were breastfed at 2 weeks of age. Exclusive breastfeeding at 1 month of age halved the risk, partial breastfeeding at the age of 1 month also reduced the risk of sudden infant death syndrome, but after adjustment this risk was not significant. Being exclusively breastfed in the last month of life/before the interview reduced the risk, as did being partially breastfed. Breastfeeding survival curves showed that both partial breastfeeding and exclusive breastfeeding were associated with a reduced risk of sudden infant death syndrome.
CONCLUSIONS. This study shows that breastfeeding reduced the risk of sudden infant death syndrome by ∼50% at all ages throughout infancy. We recommend including the advice to breastfeed through 6 months of age in sudden infant death syndrome risk-reduction messages.
Comments
Formula Feeding Raises Risk of SIDS
When research is done, the convention is to use the biological default as the null hypothesis. Since human beings are mammals, our own milk would be the default. In that case, we must talk about the relative risks of feeding human infants formula. Sadly, this study will most likely be reported with headlines that say "Breastfeeding reduces SIDS" - and most readers will never even have the opportunity to consider that with breastfeeding as the null hypothesis, the headline should instead read, "Formula feeding increases risk" - and a by a considerable amount.
Conflict of Interest:
None declared
Breast feeding, bed sharing & SIDS
Dear Sir,
Venneman, Bajanowski, Brinkmann et als’ article(1) on the reduction of risk of SIDS associated with breast feeding largely confirms previous findings. In 1965 Carpenter and Shaddick(2) compared 110 cases of sudden unexplained deaths in infancy with 196 normal controls matched for age and sex. They reported that at ages 0, 0.5, 1, 2, & 3 months 56.3%, 38.8%, 24.7%, 8.8%, and 5.6 % of cases were fully breast fed compared with 70.4%, 58.1%, 41.8%, 26.5%, and 21.6% of controls at those ages. These percentages, presented as a graph similar the Vennemann et al’s, used all available records at each age.
Comparing these percentages with Venneman et al’s Fig.2, it may be seen that initial breast feeding rates were similar for controls and much higher for the cases. However, forty years ago the duration of breast feeding in for both cases and controls was much shorter so that only 21.6% of controls were fully breast fed at 3 months compared with 50% in the later study.
Discriminant analysis, which approximates to multiple logistic regression(3) showed that bottle feeding at two weeks, shared bed, soft pillow, found with bedding partly or completely covering mouth and nose, and respiratory symptoms were significant risk factors(2).
When identifying infants at increased risk of SIDS at or soon after birth, intention to breast feed has been associated with a highly significant reduction of risk(4). However, the CESDI SUDI study(5) and the ECAS study(6) found that risk associated with bottle feeding from birth was accounted for by factors detailing the circumstances of death, in contrast to this new German study(1). However, when the type of feeding in the last 7 days was included in the ECAS model the odds ratio for complete breast feeding vs. bottle feeding was 0.50 with 95% CI (0.33–0.76) after adjusting for 17 covariables(7). This suggested a reduction of risk that was less but not significantly less than Vennemann et al’s findings(1).
Estimated reduction in risk associated with partial breast feeding differs between the studies. In the London and Cambridge study2, the percentage of infants partially breast fed was greater for cases than for controls at every age, suggesting that partial breast feeding was associated with increased risk. In the ECAS study, the adjusted OR for partial breast feeding in the last 7 days vs. bottle feeding is 0.85 and is not significant(7). Vennemann et al’s Fig 1 shows the percentage of cases and controls fully and partially breast fed by age. Superimposing Fig 1 on Fig 2, it can be seen that the percentage of cases and controls partially breast fed is similar up to 3 months of age. Thereafter the percentage of controls partially breast fed progressively exceeds that of the cases. This suggests that partial breast feeding in the first two months may not be protective. The differences in estimates of the benefit of partial breast feeding between the ECAS findings(7) and Vennemann et al’s more recent findings(1) may be due to changes in the prevalence of other risk factors to which infants are exposed and the nature of the supplements infants were and are given.
Finally, the ECAS analysis(7)showed that bed sharing is associated with prolongation of breast feeding. However, the reduction of risk associated with breast feeding is cancelled out by the increased risk associated with bed sharing.
R.G. Carpenter Medical Statistics Unit, London School of Hygiene & Tropical Medicine, London, England.
References
1. Vennemann MM, Bajanowski T, Brinkmann B, Jorch G, Yücesan K, Sauerland C, Mitchell EA, and the GeSID Study Group. Does breastfeeding reduce the risk of Sudden Infant Death Syndrome? Pediatrics 2009; 123: e406-e410.
2. Carpenter RG, Shaddick CW. Role of infection, suffocation, and bottle feeding in Cot Death. Brit J Prev Soc Med. 1965; 19: 1–7.
3 Carpenter RG. Scoring to provide risk-related primary health care: evaluation an up-dating during use. J Royal Statist Soc. Ser A 1983; 146: 1–32.
4. Carpenter RG, Gardner A, Mcweeny PM, Emery JL. A multistage scoring system for identifying infants at risk of sudden death. Arch Dis Childh. 1977; 52: 606–12.
5. Fleming P, Bacon C, Blair P, Berry PJ. Sudden unexpected deaths in infancy. The CESDI SUDI studies 1993–1996. Stationery Office. 2000. London.
6. Carpenter R, Irgens LM, Blair, P et al. Sudden unexplained infant death in 20 regions in Europe: Case control study. Lancet 2004; 363: 185–91.
7 Carpenter RG. The hazards of bed sharing. Paediatrics & Child Health (Canada) 2006. 11: Suppl A: 24A–28A.
Conflict of Interest:
None declared