American journal of obstetrics and gynecology
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Am. J. Obstet. Gynecol. · Nov 1996
The role of oxytocin receptors and vasopressin V1a receptors in uterine contractions in rats: implications for tocolytic therapy with oxytocin antagonists.
The objective of the study was to determine in the rat model whether the uterotonic action of vasopressin is mediated by the vasopressin V1a receptor in the uterus, by the oxytocin receptor, or by both. The purpose is to assess whether the anti-V1a activity of oxytocin antagonists is a desirable pharmacologic property in tocolytic therapy for preterm labor. ⋯ The parallel dose-response curves for oxytocin and arginine vasopressin suggest that the uterotonic action of vasopressin is also mediated by the oxytocin receptor. Arginine vasopressin binds to both oxytocin and V1a receptors in the uterus, but the activation of V1a receptors appears not to be a mechanism involved in the uterine-stimulating action of vasopressin. The anti-V1a activity of oxytocin antagonists does not contribute to tocolytic efficacy and may represent an undesirable side effect. By blocking the vascular V1a receptors, it may compromise the patient's ability to maintain arterial blood pressure during hemorrhage.
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Am. J. Obstet. Gynecol. · Oct 1996
Randomized Controlled Trial Clinical TrialPrevention of maternal hypotension by epidural administration of ephedrine sulfate during lumbar epidural anesthesia for cesarean section.
Our purpose was to determine whether epidural administration of ephedrine sulfate simultaneously with induction of lumbar epidural anesthesia for nonemergency cesarean section reduces the incidence of maternal hypotension. ⋯ Prophylactic epidural administration of ephedrine sulfate does not reduce the incidence of maternal hypotension after lumbar epidural anesthesia for nonemergency cesarean section.
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Am. J. Obstet. Gynecol. · Oct 1996
The preterm prediction study: risk factors in twin gestations. National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network.
Our purpose was to determine the association between the presence of bacterial vaginosis, fetal fibronectin, and a short cervix and the risk of spontaneous preterm birth of twins. ⋯ Most known risk factors for spontaneous preterm birth were not significantly associated with spontaneous preterm birth of twins. At 24 weeks, cervical length < or = 25 mm was the best predictor of spontaneous preterm birth at < 32 weeks, < 35 weeks, and < 37 weeks. Of the risk factors evaluated at 28 weeks, fetal fibronectin was the only statistically significant predictor of spontaneous preterm birth at < 32 weeks.
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Am. J. Obstet. Gynecol. · Oct 1996
Randomized Controlled Trial Clinical TrialPositional effects on maternal cardiac output during labor with epidural analgesia.
Our purpose was to test the hypothesis that the supine versus the lateral position is associated with a greater decrement in cardiac output after epidural analgesia in labor. ⋯ In contrast to the lateral position, the supine position is associated with a significant postepidural decrement in cardiac output, not identified by a change in heart rate. This likely reflects an inability to maintain stable preload volume in the supine position.
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Am. J. Obstet. Gynecol. · Oct 1996
Selective reduction of multifetal pregnancies to twins improves outcome over nonreduced triplet gestations.
Our purpose was to evaluate effects of multifetal pregnancy reduction on pregnancy complications and birth weights of remaining twin fetuses compared with expectantly managed triplets and nonreduced twins. ⋯ Multifetal pregnancy reduction results in pregnancy complications, gestational age, and birth weights closer to those of nonreduced twins than to expectantly managed triplets.