Biological Timekeeping During Pregnancy and the Role of Circadian Rhythms in Parturition

摘要: A considerable body of evidence suggests that both the hour onset labor and birth in humans, as well many animal species, is related to time day. In over 30 studies have demonstrated such a relationship, with peak hours between 2300 0400 hours. day-active animals similar pattern exists, while night-active species reverse holds. Underlying 24-h periodicity may be rhythm uterine myometrial activity. rhesus macaques, contractions show rhythmicity activity 0300 The mechanism responsible for daily rhythms proposed reflect patterns endocrine secretion. Several hormones maternal fetal circulation, including melatonin, Cortisol (mother only), dehydroepiandrosterone (fetus progesterone, also been shown demonstrate rhythms, although not all these studied any one species. Evidence sheep demonstrates circadian melatonin mediates effect photoperiod controls neuroendocrine system regulating reproduction. Extending this concept timing parturition, we raise possibility conveys information about synchronizes various light-dark cycle. We hypothesize temporal coordination environmental plays key role initiation parturition.