To compare the tocolytic efficacy and side effects of parenteral and oral magnesium and terbutaline.
Methods
Ninety-eight patients in labor between 23-35 weeks were prospectively entered into a controlled trial of intravenous and oral magnesium versus subcutaneous and oral terbutaline. Tocolytic effectiveness was judged by delay of delivery for 48 hours or 1 week, and to 37 weeks or more. The need to change therapy to the alternate drug was identified, as were side effects. Entrance characteristics of the population, initial pelvic examination, and concomitant infection or cervicovaginal isolates were noted. Outcomes included gestational age at delivery, birth weights, and Apgar scores. Outcome analysis was based on initial tocolytic therapy.
Results
Significantly more patients in the magnesium group delivered at 37 weeks or more: 34 of 46 versus 27 of 52 (P < .05). No significant differences were found for delivery by 48 hours or 1 week. The interval between treatment and delivery was greater for magnesium: 7.1 +/- 3.9 versus 5.0 +/- 3.2 weeks (P < .005). Failure to achieve 37 completed weeks was more often due to obstetric complications than to preterm labor itself. Tocolytic effectiveness was reduced if secondary therapy or re-treatment was required or if the patient had cervical dilatation of 3 cm or greater. Infectious complications were common but were not associated with tocolytic effectiveness. Side effects were more noticeable with oral magnesium and subcutaneous terbutaline.
Conclusions
For short-term tocolysis, no significant difference was found between magnesium and terbutaline. Magnesium was associated with a higher term delivery rate. Idiopathic preterm labor accounted for only a small part of the overall prematurity in the study population.
Chau, A. C., Gabert, H. A., & Miller, J. M. (1992). A prospective comparison of terbutaline and magnesium for tocolysis. Obstetrics and gynecology, 80(5), 847-851.
Chau AC, Gabert HA, Miller JM. A prospective comparison of terbutaline and magnesium for tocolysis. Obstet Gynecol. 1992;80(5):847-851.
Chau, Ann C., et al. "A prospective comparison of terbutaline and magnesium for tocolysis." Obstetrics and gynecology, vol. 80, no. 5, 1992, pp. 847-851.
We compared nifedipine and ritodrine for treatment of preterm labor with respect to neonatal outcome. We conducted an open randomized multicenter study of neonatal outcome in 185 women who received either oral nifedipine (n = 95) or intravenous (IV) ritodrine (n = 90) for treatment of preterm labor. Secondary outcome measures included neonatal mortality and morbidity, especially neonatal intensive care unit (NICU) admission, respiratory distress syndrome (RDS), and intracranial bleeding. There were no significant differences in umbilical artery pH values and Apgar scores between groups. Nifedipine was associated with lower admission rates to the NICU (49% versus 66%; odds ratio 0. 51, confidence interval 0.28, 0.93) compared with ritodrine, and lower incidences of RDS (21% versus 37%; 0.46, 0.24, 0.89), intracranial bleeding (18% versus 31%; 0.48, 0.24, 0.96), and neonatal jaundice (52% versus 67%; 0.53, 0.29, 0.97). Logistic regression analysis showed that even after correction for gestational age at birth, newborn risk of RDS, intracranial bleeding, or neonatal jaundice was significantly lower in the nifedipine group than the ritodrine group. Nifedipine for treatment of preterm labor was associated with a lower incidence of neonatal morbidity than ritodrine. That difference appeared to be partly because of the higher tocolytic efficacy of nifedipine and partly because of an intrinsic beneficial effect of nifedipine, or the lack of harmful effects when compared with ritodrine.
To examine the effectiveness of any tocolytic compared with a placebo or no tocolytic for preterm labor. We checked MEDLINE (1966-1998) and the Cochrane Controlled Trials Register for articles, using the search terms "randomized controlled trial" (RCT), "preterm labor," "tocolysis," "betamimetics," "ritodrine," "terbutaline," "hexaprenaline," "isoxuprine," "prostaglandin synthetase inhibitors," "indomethacin," "sulindac," "calcium channel blockers," "nifedipine," "oxytocin receptor blockers," "atosiban," "nitroglceride," and "magnesium sulfate." We included all RCTs that compared effect of a tocolytic with a placebo or no tocolytic in women in preterm labor, and reported perinatal, neonatal, or maternal outcomes. Studies were excluded if loss to follow-up exceeded 20% of those originally enrolled, or if data were not reported on a per-patient-treated basis. Eighteen of 76 articles retrieved met the inclusion criteria. TABULATION, INTEGRATION, Two authors independently reviewed the articles and abstracted the data. Discrepancies were resolved by consensus. Meta-analyses (odds ratio [OR] and 95% confidence interval [CI]) were done for each outcome for all trials and for specific types of tocolytic therapy when possible. Tocolytics decreased the risk of delivery within 7 days (OR 0.60, 95% CI 0.38, 0.95). Betamimetics, indomethacin, atosiban, and ethanol, but not magnesium sulfate, were associated with significant prolongations in pregnancy. Tocolytics were not associated with improved perinatal outcomes. Maternal side effects significantly associated with tocolytic use were palpitations, nausea, tremor, chorioamnionitis, hyperglycemia, hypokalemia, and need to discontinue treatment. Although tocolytics prolong pregnancy, they have not been shown to improve perinatal or neonatal outcomes and have adverse effects on women in preterm labor.
To determine whether long-term intravenous (IV) tocolysis using combined terbutaline and magnesium sulfate is safe and effective. One thousand consecutive women in preterm labor were treated with combination IV tocolytic therapy. Terbutaline was initiated with an infusion rate of 1.75 micrograms/minute and increased to a maximum of 80 micrograms/minute. Magnesium sulfate was infused at 2 g/hour without any bolus and increased to maintain a serum level of 6.5-7.5 mg/dL. Tocolysis was continued until fetal lung maturity was achieved or delivery occurred. Combination tocolytic therapy prolonged pregnancy by a mean (+/- standard deviation) of 61 +/- 23.6 days in 751 women with intact membranes and by 20.5 +/- 17.4 days in 249 with ruptured membranes. The longest durations of continuous IV tocolysis were 123 days in a patient with intact membranes and 77 days in one with ruptured membranes. The most common side effects were nausea and vomiting, followed by chest tightness and shortness of breath. Long-term IV tocolysis appeared to be safe and to have acceptable side effects, allowing patients to receive combined terbutaline and magnesium sulfate until delivery.
Nine patients in preterm labor requiring long-term tocolysis were managed with subcutaneous terbutaline administered via a portable infusion pump. All had failed oral tocolytic therapy and were therefore faced with prolonged hospitalization. In this feasibility study, the patients were treated at home and monitored with portable tocodynamometers and home nursing visits. Uterine activity data were transmitted via telephone to the study center and terbutaline pump infusion rates were adjusted accordingly. Terbutaline pump therapy consisted of a combination of low-dose continuous basal infusion supplemented with intermittent high-dose boluses. Total daily drug dosage remained exceptionally low (less than 3 mg/24 hours). The mean gestational age at initiation of therapy was 29.6 +/- 3.7 weeks, and pregnancy was prolonged an average of 9.2 +/- 4.3 weeks. The minimum gestational age at delivery was 37.3 weeks. Patient tolerance was excellent and, in a total 394 patient-days of therapy, there were no significant complications. We conclude that the portable subcutaneous terbutaline pump may be a promising new method for long-term outpatient tocolysis in patients who cannot be maintained on oral therapy.