Amniotic fluid nucleosome in pregnancies complicated by preterm prelabor rupture of the membranes

Objective: To determine the amniotic fluid nucleosome concentrations in pregnancies that are complicated by preterm prelabor rupture of membranes and their correlation to microbial invasion of the amniotic cavity (MIAC), histologic chorioamnionitis (HCA), and their association with neonatal outcomes. Methods: Eighty-nine women with singleton pregnancies were included in this study. Amniotic fluid was collected, and nucleosome concentration in the amniotic fluid was determined using enzyme-linked immunosorbent assay. Result: There were no differences observed in the amniotic fluid nucleosome concentrations in women with or without MIAC. The presence of HCA (with chorioamnionitis: median 0.5; without chorioamnionitis: median 0.21; p = 0.01) and funisitis (with funisitis: median 0.85; without funisitis: median 0.22; p = 0.0008) was associated with higher nucleosome concentrations using crude analysis; however, this was not significant after adjusting for gestational age (p = 0.12 for both). A negative correlation was observed between amniotic fluid nucleosome concentrations and gestational age (rho = -0.52; p < 0.0001). There was no association identified between amniotic fluid nucleosome concentration and neonatal morbidity. Conclusions: Amniotic fluid nucleosome concentrations remained a stable physiologic constituent in pregnancies complicated by preterm prelabor rupture of membranes, and these concentrations were gestational age dependent. Neither MIAC nor HCA significantly affected amniotic fluid nucleosome concentrations.