Cooperstock M, England J E, Wolfe R A
Department of Child Health, University of Missouri School of Medicine, Columbia.
Obstet Gynecol. 1987 Dec;70(6):852-5.
Normal labor begins most frequently between midnight and 2 AM, presumably because of an unidentified circadian labor-activating mechanism. We used records of the Collaborative Perinatal Project to determine whether such a circadian mechanism is present with intrauterine growth retardation (IUGR) or preterm birth, and whether chorioamnionitis is associated with alternative patterns. In the absence of chorioamnionitis, both preterm births and term births with IUGR demonstrated nocturnal labor onset distributions like those of control term deliveries, which had a peak incidence at 1:45 AM and an amplitude of 35%. With chorioamnionitis, in contrast, there was a different circadian distribution of term labor onset hour, with a peak at 7:45 PM and a 32% amplitude. A similar trend was found among preterm births. These data suggest the presence of the normal nocturnal labor-activating mechanism in both growth-retarded term deliveries and a defined subset of preterm deliveries. Chorioamnionitis appears to be associated with a prominent, unidentified alternative labor-activating mechanism that is maximal in the evening.
正常分娩最常发生在午夜至凌晨2点之间，推测是由于一种尚未明确的昼夜节律性分娩激活机制。我们利用围产期协作项目的记录来确定这种昼夜节律机制在宫内生长受限（IUGR）或早产情况下是否存在，以及绒毛膜羊膜炎是否与其他模式相关。在没有绒毛膜羊膜炎的情况下，早产和伴有IUGR的足月分娩的夜间分娩开始分布情况与对照足月分娩相似，对照足月分娩在凌晨1:45发病率最高，幅度为35%。相比之下，在绒毛膜羊膜炎的情况下，足月分娩开始时间的昼夜分布不同，在晚上7:45达到峰值，幅度为32%。在早产中也发现了类似趋势。这些数据表明，在生长受限的足月分娩和特定的早产亚组中都存在正常的夜间分娩激活机制。绒毛膜羊膜炎似乎与一种突出的、尚未明确的替代分娩激活机制有关，这种机制在晚上最为明显。
