Beyond international rankings of infant mortality: How the United States compares with Europe

Background:  Recent declines in infant mortality and preterm birth in the US suggested the need for a new analysis of the components of international infant mortality rankings.    

 Methods: 2010 data from the US linked birth/infant death data set and the 2^nd European Perinatal Health Report were used to compare gestational age distributions, and gestational age-specific infant mortality rates between the United States and  Europe. Kitagawa analysis was used to assess the contribution of various factors to infant mortality differences.  Events at <24 weeks of gestation were excluded to minimize possible reporting differences between countries.  Gestational age was measured via the obstetric estimate.   

 Results:  After excluding events at <24 weeks, the US infant mortality rate was 4.5 infant deaths per 1,000 live births, compared to 2.1 for Finland and Sweden. The Kitagawa analysis identified two factors that explained most of the US’s high infant mortality rate when compared to Europe:  1) The US’s higher percentage of preterm births which has been associated in the US with high rates of medical intervention (cesarean section and induction of labor); and 2) The US’s higher gestational age-specific infant mortality rate for full-term (37+ week) infants, much of which is due to causes of death that are at least partially preventable, such as SIDS and injuries.    

 Discussion: Although the recent decline in the US infant mortality rate is encouraging, international comparisons show that there is still considerable room for further improvements in US infant mortality.