***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: 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 , r and omized controlled trial RESULTS A r and omized 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 r and omly assigned to receive either ritodrine intravenously or nifedipine orally . Fifty-five women were r and omized 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 Twenty-nine women with premature labor were r and omly assigned to a ritodrine ( N = 14 ) or placebo ( N = 15 ) drug group . The 2 groups were of similar age , parity , weight , gestational age , and cervical change at the onset of treatment . They were treated sequentially with intravenous , intramuscular , and oral drugs and monitored carefully during therapy . There was a significant increase in both the maternal and fetal heart rates during ritodrine treatment , and also a significant decrease in maternal blood pressure .  Ritodrine-treated women often complained of palpatations . There was no significant difference in the extension of pregnancy , birth weight , or infant survival for the ritodrine group . Although the 1-minute Apgar scores in the ritodrine group were higher , the 5-minute scores were similar in both groups 106 women between 24 and 33 weeks ' gestation and in preterm labour , rigidly defined to include cervical dilatation plus regular uterine contractions , were r and omly allocated to receive either intravenous ritodrine hydrochloride or no tocolytic treatment . Ritodrine treatment significantly delayed delivery for 24 hours or less but did not significantly modify the ultimate perinatal consequences of preterm labour Objective We compared nifedipine and ritodrine for treatment of preterm labor with respect to neonatal outcome . Methods We conducted an open r and omized 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 In a 2‐year ( 1990‐92 ) prospect i ve national investigation , comprising all stillborn and live‐born ELBW infants with a birthweight of ≤1000 g born at 23 completed weeks of gestation or more , we examined the incidence , neonatal mortality , major morbidity and infant survival in relation to level of care and place of residence . A total of 633 ELBW infants were live‐born , i.e. 0.26 % of all live‐born infants , and 298 were stillborn .  The average neonatal mortality was 37 % and 91 % at 23 weeks , 70 % at 24 weeks , and 40 % at 25 weeks of gestation . Of neonatal survivors , 8 % had intraventricular haemorrhage grade 3,10 % retinopathy of prematurity of stage ≥3 , 2 % necrotizing enterocolitis , and 28 % were oxygen‐dependent at a time corresponding to 36 weeks of gestation . In all , 77 % were treated with  mechanical  ventilation , whereas 19 % survived without , almost all of them being CPAP treated . Infant mortality among infants born at level III ( tertiary centres ) was 30 % , at level Ha ( with full perinatal service ) 46 % and at level IIb ( with basic neonatal service ) 55 % . Only 1 % was born at hospital level I. Regarding the relation to place of residence , the mortality rates among infants residing in the areas served by levels III , IIa and lib hospitals were 36 % , 45 % and 41 % , respectively . The referral system thus functioned well , but can be improved , and increased perinatal referral , at borderline perinatal viability , might provide a better quality of care and a better chance of survival The effect of terbutaline , a " selective " beta2-receptor stimulator , was compared with that of placebo in 30 patients in premature labor . Treatment consisted of an intravenous infusion for at least 8 hours , and then of subcutaneous injections four times daily for 3 days together with peroral treatment , which was continued until the end of week 36 of pregnancy . In 12 of 15 terbutaline-treated patients ( 80 per cent ) premature labor was arrested beyond the treatment period , compared with three of 15 in the placebo group ( 20 per cent ) . This difference is statistically significant ( p less than 0.01 ) . No serious side effects were observed . During infusion , there was an increase in maternal heart rate . This was more pronounced in the terbutaline group ( 30 per cent ) than in the placebo group ( 9 per cent ) . There were no adverse effects on blood pressure , but fetal tachycardia was observed more frequently in the terbutaline than in the placebo group . The results suggest that terbutaline is a safe , potent , and well-tolerated inhibitor of premature labor Objective To compare the efficacy of tocolysis with specific regimens of nifedipine and ritodrine .  Maternal side effects and neonatal outcome also were evaluated In the etiology of premature labor prostagl and ins fulfill a significant role . It is known that indomethacin is a strong inhibitor of prostagl and in synthesis . The effect of indomethacin on premature labor  was studied in a prospect i ve r and omized double-blind study in 36 patients . Eighteen patients received indomethacin and eighteen received placebo .  200 - 300 mg of indomethacin was the total dosage in a 24 hours period . The activity of the uterus was monitored with a cardiotocograph . The mean duration of pregnancy and the mean birth weight in indomethacin group ( 36.4 weeks , 2833 g ) were both significantly greater ( p less than 0.001 ) than that in placebo group ( 31.2 weeks , 2028 g ) . In the indomethacin group 3 children weighted less than 2500 g compared with 14 in placebo group . In 15 of 18 indomethacin treated patients ( 83.3 % ) premature labor was arrested after indomethacin treatment compared with 4 of 18 in the placebo group ( 22.2 % ) . The indomethacin group had a mean 1 minute APGAR score of 9.3 + /- 0.2 whereas the placebo group showed a score of 7.8 + /- 0.5 ( p less than 0.01 ) . Three infants died from respiratory distress syndrome ; one in the indomethacin group ( 1810 g ) and two in the placebo group ( 600 and 1450 g ) . Autopsies in the infants demonstrated a typical picture of pulmonary atelectasis and hyaline membranes . There was no evidence of premature closure of the ductus arteriosus or pulmonary hypertension . 2 mothers in the indomethacin group suffered minor discomfort i.e. nausea , vomiting and vertigo . ( ABSTRACT TRUNCATED AT 250 WORDS Magnesium sulfate has been recommended as a safe and effective agent for inhibiting preterm labor . Its reported adequacy as a tocolytic agent , however , has not been substantiated by r and omized , controlled trials . To assess the efficacy of magnesium sulfate , we initiated a prospect i ve , r and omized study comparing the capabilities of magnesium sulfate , terbutaline and a placebo ( 5 % dextrose in lactated Ringer 's solution ) for labor inhibition . The study population consisted of 54 patients between 26 and 34 weeks of gestation and in preterm labor . The diagnosis of labor was made if , following hydration , persistent uterine contractions occurred at a frequency of at least three in a ten-minute period and cervical examination suggested active labor . Success was defined as postponement of delivery for at least 48 hours after initiation of therapy . Despite a trend toward increased efficacy in the terbutaline group there were no significant differences between the three treatment groups with regard to capability of delaying delivery at least 48 hours . Also , there were no significant differences between the groups with regard to gestational age at delivery , birth weight and neonatal survival . The fact that delivery occurred in less than 48 hours of approximately one-half the patients under the best of circumstances emphasizes the need for more effective techniques for the inhibition of preterm labor and the need for a better underst and ing of the mechanisms involved in the initiation of preterm labor BACKGROUND Primary pulmonary hypertension is a progressive , fatal disease of unknown cause . Vasodilator drugs have been used as a treatment , but their efficacy is uncertain . METHODS We treated 64 patients with primary pulmonary hypertension with high doses of calcium-channel blockers . Patients who responded to treatment ( defined as those whose pulmonary-artery pressure and pulmonary vascular resistance immediately fell by more than 20 percent after challenge ) were treated for up to five years . Their survival was compared with that of the patients who did not respond and with patients enrolled in the National Institutes of Health ( NIH ) Registry on Primary Pulmonary Hypertension . Warfarin was given to 55 percent of the patients as concurrent therapy , on the basis of a lung scan showing nonuniformity of pulmonary blood flow ( 47 percent of patients who responded and 57 percent of those who did not respond ) . RESULTS Seventeen patients ( 26 percent ) responded to treatment , as indicated by a 39 percent fall in pulmonary-artery pressure and a 53 percent fall in the pulmonary-vascular-resistance index ( P less than 0.001 ) . Nifedipine ( mean [ + /- SD ] daily dose , 172 + /- 41 mg ) was given to 13 patients , and diltiazem ( mean daily dose , 720 + /- 208 mg ) was given to 4 patients . After five years , 94 percent of the patients who responded ( 16 of 17 ) were alive , as compared with 55 percent of the patients who did not respond ( 26 of 47 , P = 0.003 ) . The survival of the patients who responded was also significantly better than that of the NIH registry cohort ( P = 0.002 ) and patients from the NIH registry who were treated at the University of Illinois ( P = 0.001 ) . The use of warfarin was associated with improved survival ( P = 0.025 ) , particularly in the patients who did not respond . CONCLUSIONS This study suggests that high doses of calcium-channel blockers in patients with primary pulmonary hypertension who respond with reductions in pulmonary-artery pressure and pulmonary vascular resistance may improve survival over a five-year period Objective To determine whether indometh 
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These effects were significant for beta-agonists , atosiban and indomethacin , but not magnesium sulphate .
Maternal side-effects significantly associated with betamimetics were pulmonary oedema , cardiac arrhthymias and hypokalaemia .
Although calcium antagonists have not been evaluated against placebo , comparative trials with beta-agonists have shown more favourable neonatal outcomes and better prolongation of gestation .
In conclusion , the management of  threatened preterm labour  with first-line tocolytic therapy can prolong gestation .