Ritodrine in oral maintenance of tocolysis after active preterm labor: randomized controlled trial. The clinical efficacy of oral tocolytic therapy. Double-blind evaluation of ritodrine sustained release for oral maintenance of tocolysis after active preterm labour. Maintenance oral nifedipine for preterm labor: a randomized clinical trial. The influence of betamethasone and orciprenaline on the incidence of respiratory distress syndrome in the newborn after preterm labour. Oral ritodrine maintenance in the treatment of preterm labor. A placebo-controlled randomized trial of the terbutaline pump for prevention of preterm delivery. The use of micronized progesterone in the treatment of menace of preterm delivery. Randomized trial of a single repeat dose of prenatal betamethasone treatment in imminent preterm birth.
To assess the efficacy of oral ritodrine in the form of sustained-release capsules for maintenance of uterine quiescence after successful treatment of threatened preterm labor.
                We randomized 120 women with singleton pregnancy who were successfully treated for threatened preterm labor before 34 completed weeks to receive either maintenance tocolysis with two 40 mg ritodrine sustained release capsules three times a day (study group, n=62) or no treatment (control group, n=58) for three days. The primary outcome measure was the recurrent episode of threatened preterm labor within 72 hours, which was defined as regular palpable uterine contractions and change in cervical effacement or cervical dilatation on clinical examination. Secondary outcome measures included the incidence of preterm birth, neonatal adverse outcomes, and maternal side effects.
                There was no difference in the frequency of recurrent episodes of threatened preterm labor requiring another course of intravenous treatment between the study (8/62) and control (6/58) group of women (P=0.879). No differences were found between the study and control groups in any of the predefined secondary outcome measures, ie, delivery before 37 weeks (13/62 vs 7/58, respectively; P=0.288), delivery before 34 weeks (3/62 vs 1/58, respectively; P=0.682) and birth weight (3037-/+573 g vs 3223-/+423 g, respectively, P=0.862). There were more reported maternal side effects in the study group than in control group (47/62 vs 23/58, respectively; P(<0.001).
                Additional maintenance ritodrine therapy was unnecessary in women with singleton pregnancy who had an episode of threatened preterm labor successfully treated with intravenous tocolytic therapy.
                ClinicalTrials.gov Identifier: NCT00290173. Our purpose was to determine whether maintenance oral tocolytic therapy after preterm labor stabilization decreases uterine activity, reduces the rate of recurrent preterm labor and subsequent preterm birth, or improves neonatal outcome.
                Women with documented idiopathic preterm labor stabilized with acute tocolytic therapy were randomized to three groups: placebo, terbutaline 5 mg, or magnesium chloride 128 mg, all given orally every 4 hours. Patients and providers were blinded to group assignment. All subjects were enrolled in a comprehensive system of preterm birth prevention that included preterm labor education, weekly clinic visits, home uterine contraction assessment, daily phone contact, and 24-hour perinatal nurse access.
                Of the 248 patients who were randomized, 39 were delivered before discharge and 4 were lost to follow-up, leaving 205 for final analysis: 68 placebo, 72 terbutaline, and 65 magnesium. The terbutaline group had significantly more side effects than the placebo group did. All groups had otherwise similar perinatal outcomes when confounding variables were controlled for. Overall, the three groups had a preterm birth rate < 37 weeks of 55.6% delivery, < 34 weeks of 15.6%, a 20.4% rate of newborn intensive care unit admission, and a mean neonatal length of stay of 6.3 days.
                Maintenance oral tocolytic therapy did not decrease uterine activity, reduce the rate of recurrent preterm labor or preterm birth, or improve perinatal outcome. Overall improvement in perinatal outcome may be achieved with a comprehensive program of preterm birth prevention without the use of maintenance oral tocolytic therapy. To evaluate the effect of ritodrine sustained release capsules for maintaining uterine quiescence after successful treatment of active preterm labour.
                Multicentre placebo-controlled trial.
                Five teaching hospitals in the Netherlands.
                Women (n = 95) at less than 35 weeks of gestation in whom active preterm labour had been stopped with intravenous ritodrine.
                Women received either two 40 mg ritodrine sustained release capsules (n = 50) or identical placebo capsules (n = 45) three times a day for seven days.
                The proportion of women who received another course of active treatment was significantly smaller with the sustained release than with placebo (1 of 50 versus 11 of 45: P = 0.003) as was the number delivering because of preterm labour during treatment (0 of 50 versus 4 of 45: P = 0.04). There were no other significant differences between the two groups.
                Maintenance treatment with ritodrine sustained release capsules after arrest of preterm labour reduces the risk of recurrences of preterm labour that necessitate treatment or precipitate delivery. This study was undertaken to evaluate the efficacy of maintenance oral nifedipine in patients initially treated with intravenous magnesium sulfate for preterm labor.
                Patients with a diagnosis of preterm labor between 24 and 33.9 weeks' gestation were randomly assigned to receive either maintenance tocolytic therapy with oral nifedipine (20 mg every 4-6 hours) or no treatment (control) after discontinuation of magnesium tocolysis. Pregnancy and neonatal outcomes were evaluated. A sample size of 50 patients was required to detect a 10-day difference in mean time gained (beta =.2, alpha =.05). Statistical analyses were based on intent to treat. The t, chi(2), and Fisher exact tests were performed.
                Seventy-four patients were randomly assigned to receive either oral nifedipine (n = 37) or no treatment (n = 37). There were no statistically significant differences in age, race, parity, preterm delivery risk factors, enrollment gestational age, results of cervical examination, delivery gestational age, time gained, or neonatal complications between the groups. Delivery gestational age (mean +/- SD) was 35.4 +/- 3.2 weeks for patients randomly assigned to receive nifedipine and 35.3 +/- 3.2 weeks for patients who received no treatment (P =.9). Time gained during pregnancy was 37 +/- 23.9 days in the nifedipine group and 32.8 +/- 20.4 days in the control group (P =.4).
                Maintenance therapy with oral nifedipine does not significantly prolong pregnancy in patients initially treated with intravenous magnesium sulfate for preterm labor. In a randomized double-blind trial on antenatal corticosteroid treatment for the prevention of respiratory distress syndrome (RDS) a corticosteroid related beneficial effect was found. Possibly of more significance was the finding that the children born within 12 hours of their mother's admission to hospital showed a higher incidence of RDS than those born between 12 hours and one week after admission even in the placebo and untreated groups. Bèta-adrenergic drugs seemed to exert no other influence on the occurrence of RDS than can be explained by the delay of delivery. Prolonged ruptured membranes appeared to decrease the incidence of RDS to the same extent as other symptoms of threatened preterm labour. Seventy patients with preterm labor and intact membranes were initially treated with ritodrine hydrochloride to delay preterm delivery. Tocolysis beyond 24 hours was achieved in 59 patients. Fifty-five of the 59 patients were then placed on either oral ritodrine or placebo as maintenance therapy in a randomized double-blind manner. If preterm labor recurred, the sequence of intramuscular and then oral treatment was repeated. The number of days gained after initiation of intramuscular treatment was similar in both groups (oral ritodrine = 34 days, oral placebo = 36 days). In those 55 patients receiving oral treatment, there was a smaller number of relapses requiring repeat intramuscular treatment in the oral ritodrine group (1.11 in the ritodrine patient vs. 2.71 in the placebo patient, p less than 0.05), and the mean interval between beginning oral treatment and the first relapse/delivery was 5.8 days in the oral placebo group and 25.9 in those receiving oral ritodrine (p less than 0.05). Cardiovascular side effects, notably maternal tachycardia and palpitations were frequent but well tolerated. The results suggest that oral ritodrine maintenance will decrease the incidence of recurrent preterm labor in patients who have had initial successful tocolysis. To determine the efficacy of the terbutaline pump for the prevention of preterm delivery, patients in preterm labor defined by progressive cervical change underwent intravenous magnesium sulfate tocolysis (with or without oral indomethacin, as necessary), and once labor was arrested, were randomized to one of three treatment arms: terbutaline by pump, saline by pump (blinded), or oral terbutaline. If recurrent preterm labor occurred despite maximization of therapy, the treatment arm was determined and therapy was changed; saline pump and oral terbutaline were switched to terbutaline pump, terbutaline pump was switched to oral terbutaline. Patients who continued to labor were readmitted for aggressive intravenous therapy. Women randomized to the terbutaline pump (n = 15), saline pump (n = 12), and oral terbutaline (n = 15) groups were similar in terms of gravidity, parity, days of tocolysis before study entry, gestational age at entry, and cervical dilatation at entry. The mean gestational age at delivery was the same in all three groups (35 weeks), as were neonatal outcomes. Terbutaline by pump, saline by pump, and oral terbutaline appear equivalent for the prevention of preterm delivery. The terbutaline pump should remain experimental. The results of a study concerning the treatment of acute menace of preterm labor are given: beta-mimetics were administered intravenously in all cases (44) and micronized progesterone or placebo was administered orally after classical double-blind randomization (22 cases in each group). The mean index of pregnancy prolongation was the same in both groups. However the mean duration of the intravenous perfusion and the mean quantity of beta-mimetics administered intravenously were significantly reduced in the progesterone group (P less than 0.01). The mean duration of hospital stay was also significantly reduced (P less than 0.05). Cost and risks are finally significantly lessened. A single dose of prenatal betamethasone treatment decreases neonatal morbidity rates when administered within 7 days before preterm delivery. A single repeat dose or booster dose of betamethasone before delivery has been proposed to be effective, but its efficacy has not been subjected to a randomized, blinded trial.
                Women with imminent delivery before 34.0 gestational weeks were eligible if they remained without delivery for >7 days after a single course of betamethasone. After stratification, a single repeat dose of betamethasone (12 mg) or placebo was administered. The primary outcome was survival without respiratory distress syndrome or severe intraventricular hemorrhage (grade 3 or 4).
                A total of 249 mothers had been enrolled by the time the study was discontinued. All of the 159 infants in the betamethasone group and 167 in the placebo group were born before 36 weeks of gestation. The intact survival rate was unaffected and was lower than anticipated, because the gestational age-adjusted incidence of respiratory distress syndrome was higher than the population incidence. The requirement for surfactant therapy in respiratory distress syndrome was increased in the betamethasone group. According to posthoc analysis of the data for 206 infants who were delivered within 1 to 24 hours, the betamethasone booster tended to increase the risk of respiratory distress syndrome and to decrease intact survival rates.
                According to this study, a single booster dose of betamethasone just before preterm birth may perturb respiratory adaptation. These results caution against uncontrolled use of a repeat dose of glucocorticoid in high-risk pregnancies.
Available evidence does not support the use of oral betamimetics for maintenance therapy after threatened preterm labour.