Role of the Circadian System during Pregnancy and Labor in Monkey and Man

摘要

Several 24h rhythms have been observed in the mother and in the fetus during primate gestation. 24h rhythms are present in fetal plasma hormones, breathing activity, heart rate patterns and behavioral states. In the mother, 24h rhythms occur in body temperature, blood pressure and heart rate, pregnancy associated plasma hormones and myometrial activity. In addition, both pregnant non-human primates and pregnant women deliver preferentially during the night and early morning hours. In general, 24h rhythms as observed in the fetus in utero are not manifested immediately after birth. The human fetal suprachiasmatic nucleus (SCN) is still very immature at the moment of birth, supporting the hypothesis that the majority of fetal 24h rhythms are driven by the mother. Despite preexisting, ambiguous reports in the literature, the precise role of the maternal circadian system during primate pregnancy had never been studied in detail, and no data were available to establish that 24h rhythms during pregnancy are truly circadian. The thesis addresses the role of the maternal and fetal circadian system for 24h rhythms in pregnancy associated maternal plasma hormones, myometrial activity and parturition in human and non-human primate pregnancy.