Transcriptomic phenotyping of human labor myometrium.

Myometrial biopsies were collected from 31 women undergoing primary cesarean sections and were carefully phenotyped with respect to gestational age (GA), circumstances of labor onset, and clinical status at the start and end of the intervention. Cases were aggregated into groups as follows: Group 1: term birth following spontaneous onset of term labor (TL, n=5); Group 2: term birth by elective cesarean section not in labor (TNL, n=5); Group 3: PTB following spontaneous preterm labor with intact membranes (n=6); Group 4: preterm birth following PPROM (n=8); and Group 5: provider-initiated preterm birth in the absence of active labor contractions, cervical dilation or membrane rupture (n=7). Additional phenotyping of cases spontaneously committed to PTBs (Groups 3 and 4) involved presence or absence of Triple I based on cultures of amniotic fluid obtained via clinically-indicated amniocentesis. RNAs were profiled using second generation RNA sequencing. We applied RNA-sequencing of long RNA species to uncover molecular signals that could be responsible for the transition of the human myometrium from a quiescent to the contractile laboring state in term and preterm settings.