Diurnal variation is lost in preterm deliveries before 28 weeks of gestation

Please cite this paper as: Vatish M, Steer P, Blanks A, Hon M, Thornton S. Diurnal variation is lost in preterm deliveries before 28 weeks of gestation. BJOG 2010; DOI: 10.1111/j.1471-0528.2010.02526.x. Preterm delivery is the primary cause of neonatal mortality and morbidity worldwide. Labour at term occurs as a culmination of maturational events in both the fetus and maternal uterus. This process exhibits diurnal variation, with the onset of labour being more common at night. We have confirmed that this diurnal variation is present in gestations between 28 and 36 weeks, but is absent below 28 weeks. We hypothesise that this is because before 28 weeks of gestation, the onset of labour may result from a pathological rather than a physiological process. This may have important implications regarding any pharmacological approach to the prevention and/or treatment of very early preterm labour.