Bora Zivkovic, who blogs as Coturnix at A Blog Around the Clock, has a very interesting and informative post about a study of the relationship between oxytocin and the timing of labor and birth in mice.
Coturnix ponders the implications of Oxytocin in the Circadian Timing of Birth by Jeffrey Roizen, Christina E. Luedke, Erik D. Herzog and Louis J. Muglia. In the study at Washington University School of Medicine, the researchers compared onset of labor and birth of young in normal (wild-type) mice and oxytocin-deficient mice. When they shifted the light cycle in the lab, the oxytocin-deficient mice gave birth at random times, while there was no change in when the normal mice gave birth.
Coturnix kindly explains:
Of course, in hospital births of humans, oxytocin is used very directly to shift the onset of labor and actual childbirth.