Absence of circadian rhythms of preterm premature rupture of membranes and preterm placental abruption

• Data regarding circadian rhythm in the onset of spontaneous preterm PROM and PA cases are conflicting.
• This study shows that the time of onset of spontaneous moderate preterm PROM and term PA cases is characterized by a diurnal circadian pattern. However, the time of onset of very preterm PROM and PA cases seem to be characterized by an absence of a circadian pattern associated with fetal immaturity.
• Increased understanding of circadian rhythms in pregnancy and parturition may yield important insights toward an understanding of the pathophysiological processes and mechanisms leading to spontaneous preterm PROM and PA.

PurposeData regarding circadian rhythm in the onset of spontaneous preterm premature rupture of membranes (PROM) and placental abruption (PA) cases are conflicting. We modeled the time of onset of preterm PROM and PA cases and examined if the circadian profiles varied based on the gestational age at delivery.MethodsWe used parametric and nonparametric methods, including trigonometric regression in the framework of generalized linear models, to test the presence of circadian rhythms in the time of onset of preterm PROM and PA cases among 395 women who delivered a singleton between 2009 and 2010 in Lima, Peru.ResultsWe found a diurnal circadian pattern, with a morning peak at 07:32 AM (95% confidence interval, 05:46 AM–09:18 AM) among moderate preterm PROM cases (P value < .001), and some evidence of a diurnal circadian periodicity among PA cases in term infants (P value = .067). However, we did not find evidence of circadian rhythms in the time of onset of extremely or very preterm PROM (P value = .259) and preterm PA (P value = .224).ConclusionsThe circadian rhythms of the time of onset of preterm PROM and PA cases varied based on gestational weeks at delivery. Although circadian rhythms were presented among moderate preterm PROM and term PA cases, there was no evidence of circadian rhythms among preterm PA and very or extremely preterm PROM cases, underlying other mechanisms associated with the time of onset.