Melatonin and the body's internal clock timing of human childbirth

Human parturition tends to occur more frequently at night and in the early morning hours.

• Differences in the timing of parturition among mammalian species may be related to varying uterine responses to hormonal signals that correspond with the time of day.
• Melatonin, a hormone produced by the brain, may act as a circadian signal that triggers uterine contractions leading to childbirth.
• Melatonin's effects on uterine smooth muscle cells appear to enhance the action of oxytocin, resulting in stronger contractions during nighttime.
• Understanding the role of melatonin in parturition could provide insights into managing both term and preterm labor.

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