It is hard to think of a tragedy more heart-wrenching than the unexpected death of a previously healthy infant who is placed in her crib at night and dies in her sleep without warning. Crib death, or sudden infant death syndrome (SIDS) affects otherwise healthy infants, and is the leading cause of death in babies between the age of 1-12 months. While it used to be almost three times more common than it is now (according to the National Center for Health Statistics, one in 654 live-born children in 1980 died of SIDS, compared with one in 1851 in 2003), it still takes a major toll each year, with 2246 infants dying of SIDS in 2004 in this country alone. Much still needs to be understood about why it happens and how to prevent it.
There are many reasons for the reduction in the incidence of SIDS, and one of the most important appears to be the success of the "back to sleep" campaign, which has increased awareness of the importance of having infants sleep on their backs (as opposed to on their sides or bellies). This campaign was launched after it was conclusively demonstrated that babies sleeping on their backs had a much lower risk of dying of SIDS than those sleeping on their bellies. In 2005 the American Academy of Pediatrics (AAP) came out with recommendations to reduce the risk of SIDS, including "back to sleep with every sleep", the use of firm bedding and the avoidance of loose and soft bedding, avoidance of overheating, eliminating tobacco smoke exposure, avoidance of co-sleeping, and using pacifiers.
Many people have felt that breastfeeding offers protection against SIDS, though when the data from multiple studies were analyzed, they were not felt strong enough for it to be included among the recommendations. This month, however, a study published in Pediatrics (the official journal of the AAP) seems to show that it does, in fact, afford significant protection against crib death. In this case-controlled study, 333 infants who died of SIDS were compared with 998 age-matched controls from the same towns. The researchers found much higher rates of breastfeeding amongst the controls, and concluded that breastfeeding (both exclusively and in combination with bottle feeding) reduced the risk of SIDS by ~50%. This decrease in incidence persisted even after controlling for multiple variables, such as maternal smoking, pacifier use, sleep position, socioeconomic status.
While this study seems to have taken a major step forward in answering the question of whether or not breastfeeding is protective against SIDS, we still do not understand what exactly about it is protective, and it is likely a combination of many factors. The milk itself, with its antibodies and other components, protects against infection. The frequent and often prolonged physical contact with the mother may contribute to the reduced arousal threshold from sleep that has been observed in breastfeeding infants compared to bottle fed babies. The activity of suckling itself may strengthen upper airway muscle tone. But one thing is clear: there is now one more very compelling reason to encourage women to nurse their babies.
Dennis Rosen, M.D.
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