Amniotic fluid interleukin-1β and interleukin-8 concentrations: Racial disparity in preterm birth

The purpose of this study is to examine the racial differences between interleukin (IL)-1β and IL-8 concentrations in the amniotic fluid of black and white women with spontaneous preterm birth (PTB). In this study, 350 amniotic fluid samples were collected: 165 PTB cases (<36 weeks' gestation; 52 blacks and 113 whites) and 185 controls (normal term delivery >37 weeks' gestation; 87 blacks and 98 whites). Amniotic fluid IL-1β and IL-8 concentrations were measured by immunoassay. Wilcoxon nonparametric test was performed for statistical analysis. In data stratified by race, the median IL-1β concentration was significantly higher in black cases (80 pg/mL) compared to black controls (23.7 pg/mL; P <.0001), and the difference was nonsignificant in white cases (25.5 pg/mL) compared to white controls (21.3 pg/mL; P =.1). IL-8 concentration was not higher in black cases (742.2 pg/mL) compared to black controls (731.4 pg/mL; P =.9), whereas it was higher in white cases (1362.3 pg/mL) compared to white controls (533.5 pg/mL; P =.0005). Between races, IL-1β was significantly higher in blacks (P <.0001) than in whites in PTB, whereas no significant difference was noticed in IL-8 concentration between races (P =.1). In PTB, the cytokine footprint differs in the amniotic fluid between racial groups. IL-1β is higher in black and IL-8 in white PTB. These differences in the amniotic fluid cytokine concentration might not explain the racial disparity in the PTB rate, but they are suggestive of different processes of PTB in whites and blacks.