Identifying links between infant mortality rate and societal living conditions

Introduction: Infant mortality rate (IMR) has been shown to be a sensitive measure of population health, reflecting socioeconomic status, nutrition, housing, education, employment, and health care. Historical trends in IMR of Worcester, MA, the second largest city in New England, were studied to elucidate possible factors contributing to Worcester's IMR. Methods: 3000 infant death certificates were analyzed in 10-year intervals between 1906 and 2006, including: age of infant, date and cause of death, and mother's birthplace. Results: In 1906, the overall IMR was 143 (per 1000 live births) with 74/1000 due to infectious diseases. By 1936, IMR had dropped significantly to 52/1000, with only 15/1000 due to infection. IMR continued to decrease steadily and by 2006 was 5/1000, with .36/1000 attributable to infection. Conclusions: Worcester's IMR has undergone a dramatic reduction over 100 years, driven in large part by decreases in infectious causes. Interestingly, IMR secondary to infection dropped by 59/1000 from 1906 to 1936 – much higher than the 15/1000 decline during the subsequent era of modern antibiotics and vaccines. Changes in community infrastructure, hygiene, housing, nutrition, and education may well have played a substantial role in these early improvements. This is consistent with previous work demonstrating a sensitive relationship between environment and IMR. This suggests that deteriorations in living conditions during recent difficult economic times could be responsible for current high IMRs among vulnerable subpopulations in Worcester. We propose that interventions addressing societal factors could have the greatest impact in improving Worcester's IMR.