Abstract
Objective To exploit state variations in infant mortality, identify diagnoses that contributed
to reduction of the infant mortality rate (IMR), and examine factors associated with
preterm-related mortality rate (PMR).
Study Design Using linked birth-infant deaths files, we examined patterns in the leading causes
of IMR. We compared these rates at both national and state levels to find reduction
trends. Creating a cross-sectional time series of states' PMR and some explanatory
variables, we implemented a fixed-effect regression model to examine factors associated
with PMR at the state level.
Results We found substantial state-level variations in changes of the IMR (range = − 2.87–2.08)
and PMR (−1.77–0.67). Twenty-one states in which the IMR declined more than the national
average of 0.99 (6.89–5.90) were labeled as successful. In the successful states,
we found reduction in the PMR accounted for the largest decline in the IMR—0.90 fewer
deaths. Changes in the other subgroups of leading causes did not differ significantly
in successful and unsuccessful states.
Conclusion Trends in the causes of mortality are heterogeneous across states. Although its impact
is not large, reducing the percentage of pregnant women with inadequate care is one
of the mechanisms through which the PMR decrease.
Keywords
infant mortality - state-level variations - preterm birth
