Synchronization study of electrohysterography for discrimination of imminent delivery in pregnant women with threatened preterm labor

Preterm birth a common and severe pregnancy complications, causing significant health, development, and economic problems. Accurate diagnosis of imminent labor for women with threatened preterm labor (TPL) is crucial. Electrohysterography (EHG), which represents uterine myometrial electrical activity, is a potential tool for predicting preterm birth. Increased cell synchronization is fundamental to generating high-intensity and coordinated uterine myometrial electrical activity as labor approaches. The present work aimed to evaluate the synchronization measures from multichannel EHG signals to predict labor in less than 24 h (time to delivery, TTD <24 h vs. TTD≥24 h), and between imminent labor (TTD <1 week) and non-imminent labor (TTD≥1 week) in women with TPL. We computed three synchronization measures: the imaginary component of coherence, phase lag index, and weighted phase lag index (wPLI) within three specific frequency bandwidths (fast wave low (FWL): 0.1–0.34 Hz, fast wave high (FWH): 0.34–1 Hz, and whole bandwidth: 0.1–1 Hz) from 115 pregnant women (26–41 weeks of gestation). Our results revealed that multichannel EHG synchronization measures significantly increased closer to delivery (labor > non-labor, imminent > non-imminent). Indeed, wPLI in the FWH bandwidth exhibited a positive correlation with gestational age (p < 0.001，correlation coefficient = 0.35) and an inverse relationship with time to delivery (p < 0.001，correlation coefficient = −0.33). wPLI allows for better distinguishing imminent from non-imminent in women with TPL, especially for those electrode pairs in the vertical direction, which has been reported as the predominant direction of uterine activity propagation. The three synchronization measures computed in FWL and FWH bandwidth provided complementary information for predicting labor in less than 24 h and also imminent labor in women with TPL, achieving an F1-score of 93 % (84.2–93 %) and 99.5 % (85.2–99.5 %) respectively. Our results suggest that EHG synchronization analysis constitutes a new sensitive metrics to discriminate imminent labor which can be potentially used for improving preterm birth prediction and understand uterine electrical activity dynamics.