Are cribs the safest place for infants to sleep? No: evidence supports respecting informed parental preference.

The United States Consumer Product Safety Commission (CPSC) and health professionals in some industrialized countries admonish parents: “Don't sleep with your baby” and “The only safe place for babies is in a crib.”1,2 But these recommendations lack a solid scientific basis, except in special circumstances. A well-controlled study3 found that infant sleep safety is not related to beds or cribs per se but to independent factors such as how well the sleep setting is constructed and environmental factors, such as smoke (harmful) and proximity to parents (protective). The CPSC advocates cribs based on study findings4 that cannot be used to draw valid conclusions about the relative safety of cribs versus beds for several reasons. First, the study is a case series, a type of study from which relative risk cannot be calculated because of lack of information about risk exposure (the proportion of time that infants are in each setting). Second, the study addresses only rare diagnoses like “overlying,” not overall infant mortality. No consideration is given to how the uncertain risk of accidental suffocation by a sleeping parent (overlying) balances the decreased risk of sudden infant death syndrome (SIDS) in infants who sleep near parents (in the same room).3 Furthermore, controversy continues over whether accidental overlying occurs in the absence of special circumstances, such as parental intoxication. Fueling this controversy is the lack of objective or consistent criteria to determine whether an infant found dead in a parental bed was overlain or simply died of SIDS. The distinction is usually based on subjective interpretation of historical reports. Our independent review of CPSC death certificate data5 showed bias in this process, details of which are beyond the scope of this brief discussion. Despite the limitations of CPSC data, they have helped to identify problems with product construction, yielding useful information on how to make all infant settings safer, such as eliminating posts, cords, loose mattresses, and widely spaced rails. The best available data about infant sleep safety come from a large, prospective, population-based, case-control study.3 Researchers found that SIDS was not influenced by whether infants slept with parents or in a crib, but by particular circumstances of the sleeping arrangement. In both locations, SIDS was more common with the use of heavy duvets, infants sleeping while prone, socioeconomic deprivation, or smoking by the caregiver. The negative effect of smoking was magnified at least 2-fold with bed sharing, indicating the importance of smoking cessation in parents who want to sleep with their infant. Sleeping in a parental bed was not associated with an increased risk of infant death if the caregiver was a nonsmoker and not incapacitated by alcohol or exhaustion. Sleeping together on a couch, however, increased the risk 50-fold and so this arrangement should be avoided. As in other studies, infants who slept in a separate room from their parents suffered a higher SIDS rate. History demonstrates the hazards of telling parents how their infant should sleep without a sound empiric basis. For example, physicians once commonly told parents to place their infants in a prone position to sleep. Only decades later was this advice tested and prone sleep was identified as a major risk factor for SIDS. Health authorities should attempt to modify parental decisions about infant sleep only when guided by good evidence. To assert that parents jeopardize their infant by opting against a crib is not justified by available data and has some potential harms. It may subject parents to unfounded guilt and blame,2 jeopardize professional credibility,2 constrain cultural practices, impose economic hardship, undermine breast-feeding, or otherwise inadvertently compromise infant health. Primum non nocere.