Abstract
BACKGROUND: While there have been many clinical and public health efforts to improve perinatal outcomes, our understanding of how these efforts may have shaped preterm birth (PTB) racial disparities over time remains limited. The objective of this study was to describe racial disparities in PTB and its subtypes over the last four and a half decades in Massachusetts. METHODS: Using birth record data, we conducted a serial cross-sectional study of individuals who had a live birth in Massachusetts, U.S., between 1975 and 2019. We performed a trend analysis of PTB (<37 completed weeks of gestation) based on both last menstrual period (LMP) and clinical/obstetric estimates (OE), by racial group and city (Boston, Worcester). We also estimated the average proportion of PTB subtypes (medically indicated, spontaneous, unknown) by racial group. RESULTS: PTB rates were consistently highest among Black and lowest among Asian/Pacific Islander individuals. From 1975 to 2019, LMP-based rates increased as much as 3.52 percentage points (Asian/Pacific Islander) and decreased as much as 1.37 percentage points (Hispanic). From 1989 to 2019, OE-based rates increased as much as 4.08 percentage points (Asian/Pacific Islander) and decreased as much as 1.47 percentage points (Black). The PTB trend in Boston was comparable to the state-level trend while the temporal trend in Worcester differed somewhat. Among all racial groups, the majority of preterm births were medically indicated. CONCLUSION. Racial disparities on both absolute and relative scales decreased for Black and Hispanic individuals and increased for Asian/Pacific Islander individuals, when compared with White individuals.