Abstract and Introduction
Abstract
Background Infectious diseases (IDs) are an important cause of infant mortality in the United States. This study describes maternal and infant characteristics associated with infant ID deaths in the United States.
Methods Infant deaths with an ID underlying cause of death occurring in the United States were examined using the 2008–2009 Period Linked Birth/Infant Death public use data files. Average annual ID infant mortality rates for singleton infants were calculated. A retrospective case-control study was conducted to determine infant and maternal risk factors for infant ID death among low (LBW) and normal (NBW) birth weight groups. Controls were defined as infants surviving to the end of their birth year. Risk factors for infant ID deaths were determined through multivariable logistic regression.
Results An estimated 3843 infant ID deaths occurred in the United States during 2008–2009, an overall ID infant mortality rate of 47.5 deaths per 100,000 live births. The mortality rate for LBW and NBW infants were 514.8 and 15.5, respectively. Male sex, younger maternal age (<25 years), a live birth order of fourth or more and low 5-minute Apgar score were associated with increased ID death among LBW and NBW infants. Additionally, black maternal race was associated with increased ID death among LBW infants, and having an unmarried mother was associated with increased ID death among NBW infants.
Conclusions Awareness of associations with infant ID death should help in development of further strategic measures to reduce infant ID morbidity and mortality.
Introduction
Emerging, reemerging and endemic infectious diseases (IDs) are a significant concern in the United States as they contribute to substantial morbidity, mortality and financial burdens. The burden of ID hospitalizations, particularly among infants (<1 year of age), is substantial; a recent report indicated that in 2003, 42.8% of infant hospitalizations were due to IDs and the in-hospital fatality rate for infant ID hospitalizations was 0.16%.
Although IDs, when aggregated, have been shown to be an important cause of infant mortality in the United States, recent studies of infant and maternal risk factors for infant ID death have focused on specific IDs, such as diarrhea, lower respiratory tract infections, pertussis and bronchiolitis. These studies have identified associations of infant mortality with race and birth weight. Infants of black race and low birth weight (LBW) infants were shown to have higher noncongenital ID death rates in the 1980s; noncongenital infections accounted for almost 90% of infant ID deaths. Postneonates (infants at least 28 days of age) of black race or LBW were at increased risk for a noncongenital ID death. With increasing survival of LBW preterm infants and continued racial disparity in rates of LBW and LBW-related infant mortality, we expect continued importance of infant ID deaths.
The objective of the present study is to describe maternal and infant characteristics associated with infant deaths due to IDs in the United States and to further explore the role that birth weight and race have on infant ID mortality.