Race-specific trends in infant mortality: contributions of birth-weight distribution and birth-weight-specific mortality, Louisiana 1991-2002.

OBJECTIVES: To assess the race-specific trends in infant mortality rate (IMR) in Louisiana and identify changes in the birth weight distribution (BWD) and birth weight specific mortality (BWSM) and their effect on the overall infant mortality rate. METHODS: We used the state of Louisiana's period-linked birth/infant death file, 1991-2002. The difference in race-specific mortality between our study population and the reference population was partitioned into two components, BWD and BWSM, using the method developed by Kitagawa. RESULTS: The IMR among black infants was at least twice as high as that of white infants for every year except 1991. The difference in BWD is responsible for much of the differences between the IMR among blacks and whites. On average, 80% of the excess deaths among black infants were attributed to BWD; the great majority of the infants who died weighed less than 2500 grams. CONCLUSIONS: There was a significant decline in excess mortality attributable to BWSM among both blacks and whites. But despite this decline, the overall IMR for Louisiana remained high because of the higher proportion of low birth weight infants among blacks.