Diurnal variation of uterine contractility

The diurnal uterine activity in four normal women in the secretory phase of their menstrual cycles and one woman suffering from dysmenorrhea were studied in relation to concomitant hormone levels in blood (progesterone, hGH, prolactin, cortisol, vasopressin, and 15-keto-13,14-dihydro-PGF2 alpha). In the four normal women uterine activity decreased after midnight, unrelated to circulating levels of 15-keto-13,14-dihydro-PGF2 alpha. But during a dysmenorrheic episode the uterine hypercontractility pattern correlated well with levels of the PGF2 alpha-metabolite, indicating a role of endogenous-produced PGF2 alpha in this condition. The results demonstrate a diurnal rhythm, possibly related to the wake-sleep cycle. No simple associations were seen between vasopressin, cortisol, prolactin, hGH, the PGF2 alpha-metabolite, and uterine activity.