Superiority of amniotic fluid index
Volume 163 Number 3
11. Moore TR, Brace RA. Amniotic fluid index (AFI) in the term ovine pregnancy: a predictable relationship between AFI and amniotic fluid volume. In: Proceedings of the thirty-fifth annual meeting of the Society for Gynecologic Investigation, Baltimore, Maryland, March 17-20, 1988. Baltimore: Society for Gynecologic Investigation, 1988. 12. Moore TR, Cayle]E. The amniotic fluid index in normal human pregnancy. AM] OBSTET GYNECOL 1990; 16: 11 6873. 13. Brace RA, WolfE]. Characterization of normal gestational changes in amniotic fluid volume. AM] OBSTET GYNECOL 1989;161:382-8. 14. Williams RL, Creasy RK, Cunningham GC, Hawes WE, Norris FD, Tashiro M. Fetal growth and perinatal viability in California. Obstet Gynecol 1982;59:624-8.
15. Rutherford SE, Smith CV, Phelan ]P, Kawakami K, Ahn MO. Four-quadrant assessment of amniotic fluid volume. Interobserver and intraobserver variation.] Reprod Med 1987;32:587-9. 16. Phelan]P, Ahn MO, Smith CV, Rutherford SE, Anderson E. Amniotic fluid index measurements during pregnancy. ] Reprod Med 1987;32:601-4. 17. Brar HS, Platt LD. Placental vascular resistance using umbilical velocimetry in patients undergoing cesarean section for fetal distress.] Ultrasound Med; 1989;8:211-4. 18. Sarno AP ]r, Ahn MO, Brar HS, Phelan ]P, Platt LD. Intrapartum Doppler velocimetry, amniotic fluid volume, and fetal heart rate as predictors of subsequent fetal distress. I. An initial report. AM] OBSTET GYNECOL 1989; 161:1508-14.
Randomized investigation of magnesium sulfate for prevention of preterm birth Susan M. Cox, MD, M. Lynne Sherman, RN, and Kenneth J. Leveno, MD Dallas, Texas One hundred fifty-six women with preterm labor between 24 and 34 weeks' gestation were randomized to receive either intravenous magnesium sulfate or no tocolytic therapy. Magnesuim sulfate infusions of up to 3 gmlhr were used in 76 pregnancies and resulted in a mean serum magnesium concentration of 5.5 ± 1.4 mEq/L (mean ± SEM). Compared with 80 control pregnancies, magnesium sulfate tocolysis had no significant effect on duration of gestation, birth weight, neonatal morbidity, and perinatal mortality. We conclude that clinically safe infusions of magnesium sulfate are ineffective when used to prevent preterm birth. (AM J OBSTET GVNECOL 1990;163:767-72.)
Key words: Magnesium sulfate, preterm labor
Effective methods for treatment of preterm labor have become major goals in modern obstetrics because preterm birth is the leading cause of infant morbidity and mortality. A significant cause of preterm birth, labor without ruptured membranes or other obstetric complications necessitating intervention, has been the focus of several pharmacologic approaches aimed at inhibition of uterine contractions. Agents that were used include ethanol,I-4 prostaglandin synthetase inhibitors,2. 5. 6 various J3-adrenergic sympathomimetics,7-13 calcium channel blockers,14 and magnesium sulfate."·n.15-17 Side effects and clinical conditions that contraindicate the use of J3-sympathomimetics have recently directed the focus of attention to the use of magnesium From the Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center. Presented at the Tenth Annual Meeting of the Society of Perinatal Obstetricians, Houston, Texas, January 23-27, 1990. Reprint requests: Susan M. Cox, MD, Department of Obstetrics and Gynecolo/sy, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75235-9032.
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sulfate for the inhibition of preterm labor because high concentrations of magnesium ion inhibit uterine contractility. Specifically, concentrations of 8 to 10 mEq/L were observed to reduce the frequency of in vitro uterine muscle contraction, whereas magnesium levels of 20 mEq/L were necessary for complete cessation of activity. IS Several studies"- 13 • 15-17 have suggested that magnesium sulfate is a reasonably safe and effective agent for tocolysis, although no large randomized investigations comparing this therapy with untreated controls have been reported. We sought to determine if clinically safe magnesium concentrations (i.e., those
Volume 163 Number 3
11. Moore TR, Brace RA. Amniotic fluid index (AFI) in the term ovine pregnancy: a predictable relationship between AFI and amniotic fluid volume. In: Proceedings of the thirty-fifth annual meeting of the Society for Gynecologic Investigation, Baltimore, Maryland, March 17-20, 1988. Baltimore: Society for Gynecologic Investigation, 1988. 12. Moore TR, Cayle]E. The amniotic fluid index in normal human pregnancy. AM] OBSTET GYNECOL 1990; 16: 11 6873. 13. Brace RA, WolfE]. Characterization of normal gestational changes in amniotic fluid volume. AM] OBSTET GYNECOL 1989;161:382-8. 14. Williams RL, Creasy RK, Cunningham GC, Hawes WE, Norris FD, Tashiro M. Fetal growth and perinatal viability in California. Obstet Gynecol 1982;59:624-8.
15. Rutherford SE, Smith CV, Phelan ]P, Kawakami K, Ahn MO. Four-quadrant assessment of amniotic fluid volume. Interobserver and intraobserver variation.] Reprod Med 1987;32:587-9. 16. Phelan]P, Ahn MO, Smith CV, Rutherford SE, Anderson E. Amniotic fluid index measurements during pregnancy. ] Reprod Med 1987;32:601-4. 17. Brar HS, Platt LD. Placental vascular resistance using umbilical velocimetry in patients undergoing cesarean section for fetal distress.] Ultrasound Med; 1989;8:211-4. 18. Sarno AP ]r, Ahn MO, Brar HS, Phelan ]P, Platt LD. Intrapartum Doppler velocimetry, amniotic fluid volume, and fetal heart rate as predictors of subsequent fetal distress. I. An initial report. AM] OBSTET GYNECOL 1989; 161:1508-14.
Randomized investigation of magnesium sulfate for prevention of preterm birth Susan M. Cox, MD, M. Lynne Sherman, RN, and Kenneth J. Leveno, MD Dallas, Texas One hundred fifty-six women with preterm labor between 24 and 34 weeks' gestation were randomized to receive either intravenous magnesium sulfate or no tocolytic therapy. Magnesuim sulfate infusions of up to 3 gmlhr were used in 76 pregnancies and resulted in a mean serum magnesium concentration of 5.5 ± 1.4 mEq/L (mean ± SEM). Compared with 80 control pregnancies, magnesium sulfate tocolysis had no significant effect on duration of gestation, birth weight, neonatal morbidity, and perinatal mortality. We conclude that clinically safe infusions of magnesium sulfate are ineffective when used to prevent preterm birth. (AM J OBSTET GVNECOL 1990;163:767-72.)
Key words: Magnesium sulfate, preterm labor
Effective methods for treatment of preterm labor have become major goals in modern obstetrics because preterm birth is the leading cause of infant morbidity and mortality. A significant cause of preterm birth, labor without ruptured membranes or other obstetric complications necessitating intervention, has been the focus of several pharmacologic approaches aimed at inhibition of uterine contractions. Agents that were used include ethanol,I-4 prostaglandin synthetase inhibitors,2. 5. 6 various J3-adrenergic sympathomimetics,7-13 calcium channel blockers,14 and magnesium sulfate."·n.15-17 Side effects and clinical conditions that contraindicate the use of J3-sympathomimetics have recently directed the focus of attention to the use of magnesium From the Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center. Presented at the Tenth Annual Meeting of the Society of Perinatal Obstetricians, Houston, Texas, January 23-27, 1990. Reprint requests: Susan M. Cox, MD, Department of Obstetrics and Gynecolo/sy, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75235-9032.
616/22324
sulfate for the inhibition of preterm labor because high concentrations of magnesium ion inhibit uterine contractility. Specifically, concentrations of 8 to 10 mEq/L were observed to reduce the frequency of in vitro uterine muscle contraction, whereas magnesium levels of 20 mEq/L were necessary for complete cessation of activity. IS Several studies"- 13 • 15-17 have suggested that magnesium sulfate is a reasonably safe and effective agent for tocolysis, although no large randomized investigations comparing this therapy with untreated controls have been reported. We sought to determine if clinically safe magnesium concentrations (i.e., those
