We compared nifedipine and ritodrine for treatment of preterm labor with respect to neonatal outcome.
Methods
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.
Results
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.
Conclusion
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.
PMID 10725475 10725475 DOI 10.1016/s0029-7844(99)00596-7 10.1016/s0029-7844(99)00596-7
Cite this article
Papatsonis, D. N., Kok, J. H., van Geijn, H. P., Bleker, O. P., Adèr, H. J., & Dekker, G. A. (2000). Neonatal effects of nifedipine and ritodrine for preterm labor. Obstetrics and gynecology, 95(4), 477-481. https://doi.org/10.1016/s0029-7844(99)00596-7
Papatsonis DN, Kok JH, van Geijn HP, Bleker OP, Adèr HJ, Dekker GA. Neonatal effects of nifedipine and ritodrine for preterm labor. Obstet Gynecol. 2000;95(4):477-481. doi:10.1016/s0029-7844(99)00596-7
Papatsonis, Dimitri N.M., et al. "Neonatal effects of nifedipine and ritodrine for preterm labor." Obstetrics and gynecology, vol. 95, no. 4, 2000, pp. 477-481.
To compare the tocolytic efficacy and side effects of parenteral and oral magnesium and terbutaline. 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. Significantly more patients in the magnesium group delivered at 37 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 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. 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.
The medical records of 330 patients treated with terbutaline infusion for the inhibition of preterm labor were reviewed over a five-year period. In patients with intact membranes the results were uniformly good, particularly when treatment was instituted before the 30th week. Half these patients had a prolonged labor of six weeks or more; in most cases of treatment failure complications already existed on admission. In only nine patients (2.7%) terbutaline treatment was predominantly maternal tachycardia or vomiting. Two patients had chest symptoms, but in no case was pulmonary edema diagnosed. The results suggested that a low incidence of severe side effects can be obtained if the following glucose is used as the infusion medium, instead of sodium chloride; concentrated solutions are given to avoid fluid overload; the patients are carefully controlled; and the infusion is immediately reduced or stopped if signs of severe side effects appear.
Preterm birth complicates 8-10% of all pregnancies in the United States and is the leading cause of infant morbidity and mortality. Neonatal morbidity and mortality is concentrated among very low-birthweight and extremely premature infants, particularly those delivered prior to 30 weeks' gestational age. In addition to the contribution of preterm birth to neonatal morbidity and mortality, the economic costs associated with this pregnancy complication are staggering. Efforts to reduce the preterm birth rate have been largely focused on prevention and early intervention with treatment for preterm labor. Mixed results regarding the success of prematurity prevention programs have been reported, and controversy continues to surround the efficacy of tocolytic therapy in the treatment of preterm labor. Although neonatal survival for infants born at early gestational ages has steadily improved in recent years, survival of infants delivered prior to 24 weeks' gestation remains very poor. Additionally, despite this decline in neonatal mortality, the United States still lags behind most industrialized nations in infant mortality, and no change in the rate of low birthweight has occurred in recent decades. Multiple lines of evidence support a role for infection as an etiologic factor in preterm labor. Although this association has been well known for many years, a wealth of new data is emerging, linking subclinical genital tract infection with spontaneous preterm birth, particularly among pregnancies that result in birth prior to 30 weeks' gestational age as a result of spontaneous preterm labor or preterm, premature rupture of membranes. Conversely, preterm birth that occurs closer to term is less likely to be associated with genital tract infection. Improved understanding of the link between genital tract infection and preterm birth now provides an exciting potential for the development of sensitive new markers to identify women at risk and effective interventions to prevent preterm birth. A review and comment on this growing literature is provided.
Our aim was to determine the efficacy and safety of tocolytic agents currently used to treat premature labor. We carried out a comprehensive review of tocolytic agents in the treatment of premature labor. Three hundred twenty-eight studies published between 1933 and 1992 were analyzed. An analysis of randomized, placebo-controlled, clinical trials showed that magnesium sulfate is not better than placebo in the treatment of premature labor. beta-Adrenergic receptor agonists effectively stop premature labor for only 24 to 48 hours. Calcium channel blockers and oxytocin antagonists inhibit uterine contractions, but their role in stopping labor is undefined. Prostaglandin inhibitors appear to be effective in treating premature labor and have few adverse side effects. The only tocolytic drugs that might be effective are the prostaglandin inhibitors. Tocolytic agents should be used only between 24 and 32 completed weeks of gestation. Magnesium sulfate should not be used to treat premature labor. Oxytocin antagonists should be used only in experimental clinical trials. Calcium channel blockers and beta-adrenergic receptor agonists inhibit uterine contractions but do not prolong gestation for longer than 48 hours.