Oxytocin in the Circadian Timing of Birth

BACKGROUND: The molecular components determining the timing for birth remain an incompletely characterized aspect of reproduction, with important conceptual and therapeutic ramifications for management of preterm, post-term and arrested labor. METHODOLOGY/PRINCIPAL FINDINGS: To test the hypothesis that oxytocin mediates circadian regulation of birth, we evaluated parturition timing following shifts in light cycles in oxytocin (OT)-deficient mice. We find that, in contrast to wild type mice that do not shift the timing of birth following a 6-h advance or delay in the light cycle, OT-deficient mice delivered at random times of day. Moreover, shifts in the light-dark cycle of gravid wild type mice have little impact on the pattern of circadian oxytocin release. CONCLUSIONS/SIGNIFICANCE: Our results demonstrate oxytocin plays a critical role in minimizing labor disruption due to circadian clock resetting.