[Time and obstetric anesthesia: from chaotic cosmology to chronobiology]

Temporal cycles (dark/light; birth/death; etc.), along with environmental conditions (synchronizers), influence labor physiology because of the presence of endogenous clocks (oscillators) that interact with social diuturnal clues. In this review, the most important cyclic anesthetic-obstetric parameters in parturient care are listed.

Chronobiological analysis of the main events in the obstetric pathophysiology of Mulier sapiens: I) Embryogenesis - risk of teratogenesis; II) From prematurity to post-didacticism: from eutocic labor to cervical cerclage; III) Night and labor: higher incidence of nocturnal labor (physiological facilitation) and daylight cesarean section (choice of the obstetrician); IV) The moon and labor - non-conclusive results; V) The night shift in obstetric anesthesia: riskier professional contingency; VI) Phases of cesarean section: removal of the fetus: UD stage (uterotomy - delivery) as brief as possible; effective correction of hypotension and valorize pre-anesthetic fasting; VII) circadian variation of dystocia: pain; uterine contraction; blood loss; hypertension (HTN); risk of allergy and asthma. In the nocturnal phase, the intensity of contraction and risk of hemorrhage, allergy, and asthma are greater. On the other hand, HTN in eclampsia does not show circadian variation; VIII) Obstetric chronopharmacology: local anesthetics, analgesics, hypnotics, general anesthetics, and neuromuscular blockers. Chronoenergy explains the matinal peak of opioid analgesia, vespertine of local anesthetic, and nocturnal of inhalational anesthetics.

The chronobiological approach of labor anesthesia emphasizes the obstetric importance of circadian rhythmicity in labor humanization and safety.