Deaths Attributable to Injuries in Infants, United States, 1983–1991

Study Limitations

The limitations of studies that rely on information obtained from linked birth/infant death datasets have been well documented.^{4 ,5 ,15} First, the only variables available for consideration are those collected on birth and death certificates. Therefore, we were unable to assess the contribution of other important factors such as household income, parenting style, the adequacy of social support networks, the use or nonuse of protective devices, or the effects of legislative and regulatory measures such as primary seatbelt laws. Second, data obtained from birth and death certificates are not always reliable. Inaccuracies are known to exist in both the assignment of the cause of death on death certificates and in the documentation of maternal and infant factors on birth certificates.^16–20 Finally, the study period for the current manuscript was from 1983–1991. Linked datasets were not created for 1992–1994. The 1995–linked dataset was not included in the current analysis because of the lack of continuity that this would create and because there were methodologic differences in the manner in which the datasets were created. Results of preliminary analyses of data from the 1983– to 1986–linked datasets²¹ were similar to those reported in this study, confirming that associations identified in this article have remained consistent over time.

Relation to Previous Studies

In Tennessee, researchers found that low maternal education, young maternal age, and higher birth order were all associated with at least a doubling of the risk of injury-related death among children between the ages of 0 and 4 years.⁵ In the state of Washington, young maternal age, higher parity, black race, maternal smoking, and rural residence were independently associated with death caused by injury and, in Colorado, young maternal age and single marital status were important predictors of injury-related deaths.^{4 ,8} The consistency with which these sociodemographic factors are found to be associated with injuries in infants indicate that these characteristics identify high-risk populations for targeted interventions reliably. In the current study, infants born to mothers who had received no prenatal care experienced particularly high rates of death attributable to injury. Although prenatal care is unlikely to be causally linked to the risk of injury, it may serve as a proxy for a number of complex issues eg, wantedness of the pregnancy or overall use of the health care system. In any event, the first opportunity for intervention in this high-risk group may be in the hospital at the time of delivery.

Cause-Specific Analyses: Implications for Interventions

Homicide was the leading cause of death with 2345 deaths over the 9-year study (6.72/100 000 live births). This rate is probably lower than the true homicide rate as an additional 431 deaths were coded as undetermined intent, a designation that is often used for deaths that are suspicious in nature.¹⁷ In addition, a small fraction of deaths assigned to unintentional injury codes or noninjury codes may be intentional in nature.^22–26 Although certain groups, such as infants born to young or single mothers were at increased risk of homicide, even in low-risk groups, homicide was generally the leading cause of traumatic death. For example, homicide was the leading cause of death for infants born to mothers who had >12 years of education or were >20 years of age. A number of primary prevention methods including home visiting, social support, and interventions aimed at improving parenting skills were reviewed recently.²⁷ Of these, home-visiting interventions, conducted primarily in high-risk populations, showed the most promise.^27–29 However, these studies focused primarily on the reduction of nonfatal child abuse and neglect, probably because fatal child abuse is relatively infrequent.³⁰ There is a need to expand home-visiting interventions to enable evaluation of their effectiveness in preventing fatal outcomes. In addition, other approaches should be evaluated more thoroughly and new approaches should be considered.²⁷

Native American infants experienced particularly high rates of motor vehicle-related deaths (14/100 000) and in adjusted analyses were over three times more likely to die from a motor vehicle-related death than were white infants. It is estimated that, when used properly, child safety seats reduce the risk of fatal injury in a motor vehicle crash by 69% in infants.³¹ Although all 50 states have laws mandating the use of child restraints, Native Americans who live on reservations are exempt from state regulations, and tribal laws vary from one reservation to another.³² In places where legislation is not sufficient, efforts should focus on the enactment of new laws or the strengthening of existing laws. To ensure that car seats are universally available, lender programs such as those used by the Navajo nation should be established (Richard Smith, Indian Health Service, written communication, May 1998). Finally, it is estimated that >80% of child safety seats are used improperly.³³ Although parents and other caregivers should receive instructions on the correct use of child safety seats and the need to use the safety-seat every ride, the high rates of misuse also demonstrate the urgent need for products that are more user-friendly.

Birth order was an important predictive factor for deaths attributable to drownings, fires, and mechanical suffocation. This may be related to a decrease in parental supervision as the parents' attention is divided among more children. Alternatively, parents may overestimate the maturity and capabilities of older siblings and inappropriately expect them to supervise the infant. In two separate studies of bathtub drownings, >30% of victims were being supervised in the bathtub by an older sibling.^{34 ,35} Another study found that, among infants, 11% of injuries that resulted in an emergency department visit occurred while the infant was being supervised by an older sibling.³⁶ These findings emphasize the need to counsel caregivers, not only on the risks of leaving children unattended, but also on the need for appropriate adult supervision.

Consistent with findings in the current study, researchers in Tennessee identified an independent association between maternal age, education, and birth order and fire-related deaths among children <5 years of age.¹⁰ Although the specific role of siblings in fire-related deaths is unknown, it is estimated that, in the 0- to 5-year age group, ∼40% of deaths resulting from residential fires are caused by the actions of children.^{37 ,38} In addition to the installation and maintenance of smoke detectors, parents should be reminded to store matches and lighters out of the reach of young children.³⁸

One unexpected finding was the strong association between low birth weight and deaths attributable to choking. This association was seen for deaths caused by inhalation of food and for deaths caused by inhalation of objects. Of interest, 40% of deaths attributable to food inhalation and 33% of deaths caused by inhalation of objects occurred during the first 12 weeks of life, before the usual recommended age for the introduction of solid foods and before the attainment of developmental skills that would allow an infant to obtain and place an object in his/her mouth independently. Thus, although there may be a physiologic explanation for this finding, eg, oral pharyngeal coordination problems predisposing premature infants to choking episodes, it is possible that these deaths represent errors in classification. Further research is needed in this area.

From 1983–1991, the infant mortality rate in the United States decreased by 20%.¹¹ In contrast rates of death attributable to intentional injuries and unintentional mechanical suffocation increased, and there was no change in rates of motor vehicle-related deaths or drownings. A reduction in the rate of death from injury in any one of the identified high-risk groups to the level of its comparison group would result in the saving of many lives. For example, if infants of young mothers had experienced the same rate of death from injury as infants born to mothers ≥25 years of age, 4062 lives would have been spared over the 9-year study period. Clearly, there is no single intervention that will address all causes of injury. Continued efforts should focus on the implementation of proven strategies, such as proper use of child restraints for the prevention of motor vehicle-related injuries or installation and maintenance of smoke detectors for the prevention of deaths caused by fires. For some causes of injury, such as homicide, there is a need to identify and evaluate new preventive strategies. Additionally, there is a need to identify the most effective means of communicating prevention messages to high-risk populations as well as a need to identify and reduce the barriers faced in implementing prescribed preventive strategies. Although all caregivers should receive counseling in injury prevention our findings identify high-risk subgroups for enhanced, cause-specific efforts.