The Association between Prenatal Yoga and the Administration of Ritodrine Hydrochloride during Pregnancy: An Adjunct Study of the Japan Environment and Children's Study.

INTRODUCTION: While the beneficial effects of prenatal yoga have been reported in recent years, little is known about its effectiveness in pregnant Japanese women. Despite several adverse effects, ritodrine hydrochloride is frequently prescribed to suppress preterm labor in Japan, and its usage may therefore indicate cases of preterm labor. This study aimed to clarify the association between prenatal yoga and ritodrine hydrochloride use during pregnancy. METHODS: An observational study was conducted as an adjunct study by the Hokkaido unit of the Japan Environment and Children's Study. Information on prenatal yoga practice was collected using a self-questionnaire between March 21, 2012, and July 7, 2015, targeting women who had recently delivered. Ritodrine hydrochloride use was identified from medical records. A total of 2,692 women were analyzed using logistic regression models that adjusted for possible confounders. RESULTS: There were 567 (21.1%) women who practiced prenatal yoga, which was associated with a lower risk of ritodrine hydrochloride use (adjusted odds ratio [OR] 0.77; 95% CI 0.61-0.98). This was especially evident in women with a total practice duration that exceeded 900 minutes throughout their pregnancy (adjusted OR 0.54; 95% CI 0.38-0.76). A sensitivity analysis that excluded patients with threatened abortion during the study period produced similar results. CONCLUSIONS: Prenatal yoga was associated with a lower risk of ritodrine hydrochloride use, particularly in women with more than 900 minutes of practice time over the course of their pregnancy. Prenatal yoga may be a beneficial option for pregnant women in the selection of alternative therapies.

Tocolytic effectiveness of nifedipine versus ritodrine and follow-up of newborns: a randomised controlled trial.

BACKGROUND: Several studies have demonstrated the superior tocolytic effectiveness of nifedipine over ritodrine. Only 1 trial conducted a long-term follow-up of newborns and found no difference in psychosocial and motor functioning. In a randomised, multicentre trial, we compared the tocolytic effectiveness of nifedipine and ritodrine and included a long-term follow-up of the newborns after 2 years of age. METHODS: Patients with imminent preterm labour were randomised and received either nifedipine or ritodrine. Side-effects, tocolytic effectiveness and neonatal outcome were studied. Development of the children was studied after the age of 2 years by a parental questionnaire. RESULTS: Ninety-three patients were included. Birth was postponed for an average of 4.3 weeks in the ritodrine group and 5.0 weeks in the nifedipine group (p=0.4). Patients who received ritodrine experienced significantly more side-effects compared to patients who received nifedipine (29 versus 4%, p<0.05). No significant differences were found in either group for average birth weight, Apgar scores after 1 min, neonatal intensive care unit (NICU) admission and neonatal complications. Parental questionnaires after 2 years had a response rate of 70%. Two-thirds of the children had developed normally in both groups. In both groups, only a few children were severely retarded (n=4). No significant differences in development were found between the 2 groups. CONCLUSIONS: Both nifedipine and ritodrine proved effective tocolytic drugs, however ritodrine caused significantly more maternal side-effects. Neonatal outcome and long-term development after 2 years of age were not significantly different. We favour nifedipine over ritodrine as a tocolytic drug.

Nifedipine versus ritodrine for suppression of preterm labor. Comparison of their efficacy and secondary effects.

OBJECTIVES: To compare the efficacy of nifedipine and ritodrine in prolonging pregnancy beyond 48 h, 1 week and 36.0 weeks and to evaluate maternal side effects and adverse perinatal outcome. STUDY DESIGN: Non-blinded, randomized controlled trial. Eighty patients with singleton pregnancies admitted for preterm labor with intact membranes between 22 and 35 weeks of gestation were included in the study. Preterm labor was defined as the persistence of at least two symptomatic uterine contractions within a 10 min period during 60 min after admission and despite bed rest. RESULTS: Forty women received oral nifedipine and forty intravenous ritodrine. Two patients, one from each group, were excluded because of loss to follow-up after discharge. Therefore, 39 women in the nifedipine and the ritodrine groups, respectively, were evaluable for the final analysis. Baseline characteristics were comparable in both groups. The percentage of initial response, the speed of onset of action and the rate of successful treatment within 48 h were significantly better in the ritodrine group. However, prolongation of pregnancy beyond 7 days and 36 weeks of pregnancy was similar with a significantly lower rate of side effects in the nifedipine group. CONCLUSIONS: In this small trial, ritodrine provided more effective tocolysis within the first 48 h than nifedipine at the doses used in this study, although with a significantly higher rate of side effects.

Severe hyperinsulinaemic hypoglycaemia in a baby born to a mother taking oral ritodrine therapy for preterm labour.

Hyperinsulinism of infancy is a major cause of persistent hypoglycaemia in the newborn period. Transient mild self-limiting hyperinsulinaemia and hypoglycaemia have been described in neonates born to mothers taking ritodrine therapy for premature labour. Ritodrine crosses the placental barrier and enters the fetal circulation readily but the mechanism of how it causes hyperinsulinaemia and hypoglycaemia is unclear. We report the case of severe prolonged hyperinsulinaemic hypoglycamia in a neonate born to a mother taking ritodrine therapy from 16 weeks' gestation for preterm labour. The hyperinsulinaemic hypoglycaemia was managed with oral nifedipine as diazoxide was contraindicated due to fluid overload. Possible mechanisms of ritodrine-induced hypoglycaemia and insulin secretion are discussed.

[Which tocolytic drugs in case of preterm labor?]. / Menace d'accouchement prématuré: quels tocolytiques utiliser?

Because criteria used for the prediction of preterm labor are poorly effective, many patients receive tocolytic therapy in excess during pregnancy. Beta-mimetic agonists are the reference tocolytic drugs in most countries. Their efficacy in prolonging pregnancy compared to a placebo is proven although no benefit in neonatal morbidity or mortality has been demonstrated. Beta-mimetics have many contraindications, and side-effects are frequent. Serious complications such as pulmonary edema and maternal deaths, though rare, have been reported. Recent research has focused on tocolytic drugs with similar efficacy to beta-mimetics but with less side effects. Calcium-channel-blockers and oxytocin antagonists have been compared with beta-agonists in randomized trials. Both have demonstrated similar efficacy in the prolongation of pregnancy for at least 48 hours. Contrary to beta-mimetics, very few interruptions of treatment have been observed with these treatments. Other tocolytic drugs such as cyclooxygenase inhibitors, although effective in prolonging pregnancy, have unacceptable fetal side effects. Progesterone, antispasmodic drugs and magnesium sulfate have been widely used but their efficacy has not been demonstrated. More recent treatments such as NO-donors and cyclooxygenase-II specific antagonists are not sufficiently evaluated. In conclusion, three main classes may be used as first line tocolytic therapy, beta-adrenergic agonists, calcium-channel-blockers, and oxytocin antagonists. The choice among these treatments may be based on contraindications to beta-mimetics, side-effects of the treatment, or even economic reasons.

[Successful resuscitation of a patient with prolonged tocolytic therapy and an emergency cesarean section]. / Uspesna reanimacija bolesnice na produzenoj tokolitickoj terapiji kod koje je uraden hitan carski rez.

Ritodrine is the only medicament approved by FDA in the USA as well as in our country for prevention of the threatening preterm labor. Its adverse effects upon the respiratory and cardiovascular systems, including pulmonary oedema and myocardial ischemia, occur more frequently during the intravenous therapy than during the oral maintenance therapy. The aim of this report was to present a patient with cardiovascular adverse effects of ritodrine, who had her pregnancy terminated by an urgent cesarean section under general anesthesia. In the course of operation, the patient had two cardiac arrest (total of 70 min). Resuscitation was performed by direct and indirect heart massage. The patient's condition was stabilized during the next six hours. The patient was transferred to the coronary unit, where the treatment was continued for 30-days period, after which the patient was released home as completely recovered.

Nifedipine versus ritodrine for suppression of preterm labor; a meta-analysis.

BACKGROUND: Since large randomized clinical trials comparing the effectiveness of nifedipine and ritodrine in the suppression of preterm labor are lacking, we performed a meta-analysis on the subject. METHODS: We searched the databases Medline and EMBASE using the keywords 'nifedipine', 'ritodrine' and 'randomized' or 'randomised'. The studies were scored for blinding, method of randomization and type of analysis ('intention-to-treat' versus 'par protocol'). Subsequently, two by two tables were constructed using 'delay of labor by 48 hours or more', 'delay of labor beyond 36 weeks gestation', perinatal mortality, respiratory distress syndrome and admission to a neonatal intensive care unit as end points. Homogeneity between the studies was tested with a Breslow-Day test. Pooled odds ratios were calculated in case homogeneity could not be rejected. RESULTS: We could detect ten studies that were published between 1986 and 1998, incorporating data of 681 patients. Nifedipine reduced the risk of delivery within 48 hours compared to ritodrine, but this difference was not statistically significant (odds ratio 0.85, 95% confidence interval 0.54 to 1.1). Nifedipine also reduced the risk of delivery before 36 weeks compared to ritodrine, and this difference was statistically significant (odds ratio 0.59, 95% confidence interval 0.39 to 0.90). We are not aware of studies reporting on long-term outcome. CONCLUSION: Since studies reporting on long-term outcome are lacking, the choice between nifedipine and ritodrine can only be based on obstetrical and short-term neonatal outcomes. From that perspective, nifedipine should be the drug of first choice for the suppression of preterm labor.

A randomized comparison of nifedipine and ritodrine for suppression of preterm labor.

OBJECTIVES: To compare the efficacy and safety of nifedipine and ritodrine in preventing preterm labor, and to evaluate maternal side effects and neonatal outcome. STUDY DESIGN: Non-blind, randomized controlled trial RESULTS: A randomized trial of 102 pregnant women with gestational ages under 34 weeks, including 24 with twin pregnancies and 45 on betasympathicomimetic drugs, who had regular uterine contractions with either observed cervical changes or preterm rupture of membranes. After stratification women were randomly assigned to receive either ritodrine intravenously or nifedipine orally. Fifty-five women were randomized to the nifedipine group and 47 to the ritodrine group. As expected, both groups were comparable in terms of several entry variables, including mean gestational age, ruptured membranes, treatment with tocolytic drugs, cervical examination, contraction frequency, age, and twin gestation. Delivery of women in the nifedipine group was delayed for 48 h, 7 days, and until 34 weeks gestation in 33 (60%), 26 (47%) and 21(38%) cases, respectively, compared with 31 (66%), 21(45%) and 11(23%) women in the ritodrine group (no significant difference). Maternal side effects were significantly less common in the nifedipine group than in the ritodrine group, however after 7 days of therapy there was no difference between the two groups. Neonatal outcome was similar in the two groups, with four neonatal deaths in the nifedipine and five in the ritodrine group. CONCLUSIONS: Nifedipine seems to be as effective as ritodrine in the treatment of preterm labor and is associated with less frequent side effects.

Nifedipine and ritodrine in the management of preterm labor: a randomized multicenter trial.

OBJECTIVE: To compare the efficacy of nifedipine with ritodrine in the management of preterm labor. METHODS: One hundred eighty-five singleton pregnancies with preterm labor were assigned randomly to either ritodrine intravenously (n = 90) or nifedipine orally (n = 95). The principal outcome assessed was delay of delivery. RESULTS: Ritodrine was discontinued in 12 patients because of severe maternal side effects, and their results were excluded from further analysis. More women in the ritodrine group delivered within 24 hours (22 versus 11, P = .006), within 48 hours (29 versus 21, P = .03), within 1 week (45 versus 36, P = .009), and within 2 weeks (52 versus 43, P = .005) compared with those receiving nifedipine. There were significantly fewer maternal side effects in the nifedipine group. Apgar scores and umbilical artery and vein pHs were similar in both groups. The number of admissions to the neonatal intensive care unit (NICU) in the nifedipine group was significantly lower than in the ritodrine group (68.4 versus 82.1%, P = .04). CONCLUSION: Nifedipine in comparison with ritodrine in the management of preterm labor is significantly associated with a longer postponement of deliver, fewer maternal side effects, and fewer admissions to the NICU.

Ritodrine and nifedipine as tocolytic agents: a preliminary comparison.

The effectiveness of the tocolytic agent and other betamimetic drugs in the treatment of preterm labor remains controversial. Effectiveness or efficancy of ritodrine has not yet convincingly been proven. A major concern are the marked side effects of beta-mimetics. The calcium channel blocker nifedipine has been used for tocolysis shortly after its introduction in clinical practice and is considered to be a probable good alternative for ritodrine. The efficacy of nifedipine versus ritodrine in the treatment of preterm labor was assessed in a retrospective study. 32 patients received intravenous ritodrine and 29 oral nifedipine. As endpoints were used: postponement of delivery, maternal side effects and perinatal outcome. The results of this retrospective study suggest that nifedipine is more successful in postponing delivery than ritodrine. Maternal side effects seemed to occur more frequently and be more serious in patients treated with ritodrine as compared to nifedipine. Perinatal outcome seemed better in the nifedipine group than in the ritodrine group. The promising data from small prospective studies and the results of this retrospective study warrant further large prospective studies on the definitive place of nifedipine in the treatment of premature labor. Until the results of such a trial are available we advocate the use of nifedipine in case of preterm labor, especially in a patient with diabetes mellitus, ruptured membranes, cardiac disease or multiple pregnancy, in order to avoid the characteristic side effects of beta-mimetics.

Comparison of nifedipine and ritodrine for the treatment of preterm labor.

Treatment of preterm labor with beta-sympathomimetics has been questioned because of the many maternal and fetal complications associated with its use. Nifedipine, a calcium antagonist, has been shown to suppress uterine activity in vitro and in vivo. A randomized prospective study was performed to compare the efficacy of nifedipine to ritodrine in the suppression of preterm labor. Data obtained from 42 women, of which 19 were randomized to the ritodrine group and 23 to the nifedipine group, were analyzed. Ritodrine and nifedipine proved to be equally effective in the suppression of preterm labor. However, the nifedipine group had fewer maternal and fetal complications.

A comparison of tocolysis with nifedipine or ritodrine: analysis of efficacy and maternal, fetal, and neonatal outcome.

Nifedipine, a dihydropyridone calcium entry blocker, has been used with increasing frequency in the treatment of preterm labor. We studied 66 patients in this prospective, randomized trial to evaluate the efficacy and maternal, fetal, and neonatal outcome associated with tocolysis with nifedipine or ritodrine. Delivery was delayed for 48 hours, 7 days, and until the thirty-sixth week of gestation in 84%, 70%, and 41%, respectively, of patients in the nifedipine group, compared with 72%, 63%, and 52% of patients in the ritodrine group (difference not significant). Maternal side effects were more common and more serious in the group of patients who received ritodrine compared with those who received nifedipine (18 of 38 versus 5 of 38, p less than 0.01); however, fetal and neonatal outcome appeared to be similar when the groups were compared. On the basis of this study, it appears that tocolysis with either nifedipine or ritodrine is equally efficacious; however, maternal side effects are less common with nifedipine treatment. We conclude that nifedipine may have a role in the treatment of preterm labor but suggest further careful evaluation of this agent before it is considered for routine clinical use.

Nifedipine versus ritodrine for suppressing preterm labor.

Fifty-eight women in preterm labor were selected randomly to receive either oral nifedipine or intravenous ritodrine hydrochloride. In comparison to ritodrine, nifedipine had similar tocolytic efficacy with fewer adverse maternal and fetal side effects. On Doppler studies nifedipine had an insignificant effect on umbilical blood flow. Preliminary data suggest that nifedipine is a safe, effective and well-tolerated tocolytic agent. It may prove to be a suitable alternative to ritodrine hydrochloride, especially for women in whom beta-sympathomimetics are contraindicated.

[A randomized study of the treatment of threatened premature labor. Nifedipine versus ritodrine]. / Etude randomisée de traitement de la menace d'accouchement prématuré. Nifédipine versus ritodrine.

The authors compare the efficiency of two drugs in the treatment of threatened premature labour, the one being the calcium inhibitor (nifedipine) and the other a beta-mimetic drug (ritodrine). 62 patients after random selection were divided into two groups: 32 treated with ritodrine and 30 treated with nifedipine. The treatment was carried out over 7 days. The success rate was similar in both groups -72% for the ritodrine group and 63.33% for the nifedipine group. Women receiving nifedipine had slightly greater gain in weeks, six as against five for ritodrine. The side effects which were often found with nifedipine were; hot flushes (in 10 cases) and headaches (4 cases). These symptoms appeared 15-30 minutes after the first dose and were transitory. No neonatal complications were found. The ease with which a calcium inhibitor can be given suggests that it should be used more frequently in the treatment of threatened premature labour and particularly when there are contra-indications to the use of beta-mimetic drugs.

Prolonged fetal ritodrine exposure and immediate neonatal outcome.

Ritodrine hydrochloride was administered over a period of two years to a total of 200 women in premature labor. One hundred sixty-two (81 per cent) of the women carried pregnancy to 35 weeks or longer. To determine the effect of ritodrine on the neonates, the duration and amount of exposure, onset of exposure, and interval between cessation of exposure and delivery were correlated with gestational age, birth weight, Apgar scores, mortality, and the presence of hypoglycemia, hyperbilirubinemia, respiratory distress, and intrauterine growth retardation. Infants exposed for six weeks or more (long-term exposure) were significantly heavier than those exposed for shorter periods (short-term exposure), a difference that was possibly attributable to differences in gestational age at birth. Infants who were exposed as fetuses to ritodrine beginning at 30 weeks' or less gestation needed phototherapy more often than did infants whose fetal exposure began at after 30 weeks' gestation. Neither duration of exposure nor gestational age at birth was a significant factor in hyperbilirubinemia. Of infants delivered at or after 35 weeks' gestation, 32 (20 per cent) experienced early hypoglycemia; and 26 of these (81 per cent) were exposed up to the day of delivery. This outcome differed significantly from that of infants whose exposure stopped at least one week before delivery. In addition, respiratory distress syndrome was more common in those infants exposed up until delivery (34 of 36).(ABSTRACT TRUNCATED AT 250 WORDS)

Addition of magnesium sulfate improves effectiveness of ritodrine in preventing premature delivery.

From October, 1981, to July, 1983, 225 patients were evaluated for premature labor at Forsyth Memorial Hospital. Sixty-five of these patients were considered to be candidates for intravenous ritodrine treatment. Of this group, 24 patients were successfully treated and had pregnancy prolongation ranging from 1 to 17 weeks. Forty-one patients did not respond to maximal intravenous ritodrine therapy (300 to 350 micrograms/min). Eleven patients subsequently delivered within 24 to 48 hours of treatment initiation. The remaining 30 patients received intravenous magnesium sulfate (1 to 3 gm/hr) in addition to intravenous ritodrine. Eighteen patients responded favorably to this combination treatment and had pregnancy prolongation ranging from 1 to 11 weeks. Twelve patients delivered within 1 week from treatment initiation. In all cases where pregnancy prolongation was achieved, birth weight and neonatal outcome were significantly improved compared to patients who did not respond to either intravenous ritodrine alone or intravenous ritodrine and magnesium sulfate combination. Treatment related maternal/fetal complications were not significantly different in the various groups examined. From the foregoing we conclude that, in a select group of patients in premature labor not responding to conventional ritodrine therapy, magnesium supplementation in pharmacologic doses could have a beneficial effect with respect to pregnancy outcome.

Potassium supplementation in ritodrine-induced hypokalemia.

Acute hypokalemia occurs during infusion of beta 2 agonists for tocolysis. This study examines the efficacy of supplemental potassium in treating this hypokalemia. Four groups of dogs were anesthetized and given lactated Ringer's solution (group I), potassium chloride (group II), ritodrine hydrochloride (group III), and ritodrine plus potassium (group IV). Arterial blood gases, pH, and serum and urinary electrolytes were measured. Results were analyzed by an analysis of variance. Serum potassium fell in groups I and III, rose in group II, and remained stable in group IV. Urinary potassium levels in groups that received ritodrine (III and IV) were not different from control levels. Potassium given with ritodrine will prevent hypokalemia. However, the risks of hyperkalemia exist if vigorous replacement is undertaken. There were no dysrhythmias and no adverse effects in any of the hypokalemic animals. Therefore, the routine administration of potassium is not advocated even in obstetric patients who undergo general anesthesia.