The amniotic fluid cell-free transcriptome in spontaneous preterm labor

The amniotic fluid (AF) cell-free (cf) RNA was shown to reflect physiological and pathological processes in pregnancy, but its value in prediction of spontaneous preterm delivery is unknown. Here we profiled cfRNA in AF samples collected from women who underwent transabdominal amniocentesis after an episode of spontaneous preterm labor and subsequently delivered within 24h (n=10) or later (n=28) in gestation. Expression of known placental single cell (sc) RNA-Seq signatures were quantified in AF cfRNA and compared between groups. Random forest models were applied to predict time to delivery after amniocentesis. There were 2385 genes differentially expressed in AF samples of women who delivered within 24 hours of amniocentesis compared to gestational age-matched samples from women who delivered after 24 hours of amniocentesis.Genes with cfRNA changes were associated with immune and inflammatory processes related to the onset of labor, and expression of placental scRNA-Seq signatures of immune cells were increased with imminent delivery. AF transcriptomic prediction models captured these effects and predicted delivery within 24 hours of amniocentesis (AUROC =0.81). These results may inform development of biomarkers for spontaneous preterm birth. We profiled cfRNA in AF samples collected from women who underwent transabdominal amniocentesis after an episode of spontaneous preterm labor and subsequently delivered within 24h (n=10) or later (n=28) in gestation.