Weiner et al. sought the specific gene sets responsible for initiating term and preterm labor, along with the effector genes that are necessary for labor independent of gestation and underlying trigger. Myometrium was obtained from the upper pole of the transverse lower uterine segment incision of 4 groups of women at the time of their primary cesarean section: preterm not in labor and no inflammation (PTNL), preterm in labor with inflammation (PTL), term not in labor (TNL), and term labor (TL). Indications for cesarean delivery in the PTNL group were all related to preeclampsia and in the TNL were all related to breech presentation. The indication for cesarean delivery in the TL group was an arrest of cervical dilation at ≥6 cm. Patients in the PTL group all had intraamniotic inflammation.

Tissue Condition Samples
Test myometrium term labor 3
Control myometrium term not in labor 3
Gene Fold Change (log2) Significance Genus Species