***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: OBJECTIVE To observe the effect of nitroglycerin patch on treatment of preterm labour and to identify the mechanism responsible for arrest of preterm labour with nitroglycerin patch . METHODS Sixty women diagnosed as threatened preterm labour were divided into two groups : group of nitroglycerin patch therapy ( n = 30 ) , and group of magnesium sulfate and salbutamol sulfate therapy ( n = 30 ) . Nitroglycerin patch was applied to the abdomen of patients . Measurement of cortictrophin-releasing hormone ( CRH ) levels in maternal plasma was performed by radioimmunoassay . RESULTS The mean time of pregnancy prolongation was 25 days in the nitroglycerin patch group , and 8 days in the magnesium sulfate and salbutamol sulfate group . The mean level of CRH concentration in nitroglycerin patch group before treatment was ( 257 + /- 61 ) ng/L , and it was decreased sharply to ( 38 + /- 17 ) ng/L after treatment . Those were ( 248 + /- 60 ) ng/L and ( 56 + /- 22 ) ng/L respectively in the magnesium sulfate and salbutamol sulfate group . CONCLUSION Reduction of CRH secretion may be the mechanism of nitroglycerin patch on preterm labour therapy . It may act as an effective , safe , well-tolerated , and non-invasive method for treatment of preterm labour OBJECTIVE Our r and omized , double-blind , placebo-controlled trial of transdermal nitroglycerin ( GTN ) for preterm labour demonstrated a significant reduction in neonatal morbidity and mortality . The objective of this study was to evaluate developmental performance in the children born to women who participated in the GTN trial after one year and two years of follow-up . METHODS The Ages and Stages Question naires ( ASQ ) were used for the assessment s , and five domains of child development ( communication , gross motor skills , fine motor skills , problem-solving , and personal social skills ) were evaluated . Supplementary analyses were performed after stratifying study subjects by gestational age at birth ( < 28 , 28 to 32 , 33 to 36 , ≥ 37 weeks ) or by defining study subjects as normal or abnormal using st and ard cut-offs . RESULTS A total of 153 infants born to women who participated in the GTN trial were included in the initial follow-up . Among them , 111 ( 72.5 % ) children ( 55 in the GTN  arm and 56 in the placebo arm ) at 12 months of age and 83 ( 54.2 % ) children ( 42 in the GTN arm and 41 in the placebo arm ) at 24 months of age completed the full ASQ . There were no differences in ASQ total score and five subscores between the GTN arm and the placebo arm at the one-year and two-year follow-up evaluations , in overall study subjects , or after stratifying study subjects by gestational age . A trend towards reduced abnormalities in the GTN arm at the two-year follow-up was observed , although there was no statistical significance . CONCLUSION Maternal GTN use for preterm labour had no impact on children 's long-term development , but larger studies are needed to confirm the preliminary findings of this study PURPOSE to compare the effectiveness of transdermal nitroglycerin with oral nifedipine in the inhibition of preterm delivery . METHODS a clinical essay has been performed with 50 women in preterm delivery , r and omly divided into two groups , 24 receiving  oral nifedipine ( 20 mg ) , and 26 , transdermal nitroglycerin ( 10 mg patch ) . Patients with a single gestation , between the 24th and the 34th weeks and diagnosis of preterm delivery were selected . Women with fetal malformation and clinical or obstetric diseases were excluded . The variables analyzed were : effective tocolysis , time needed for tocolysis , recurrence frequency , progression to preterm delivery , and side effects . RESULTS tocolysis efficacy in the first 12 hours was similar between the groups ( nitroglycerin : 84.6 % versus nifedipine : 87.5 % ; p=0.50 ) . The time average time needed for tocolysis was also similar ( 6.6 versus 5.8 hours ; p=0.30 ) . There was no difference between the groups , concerning the recurrence of preterm delivery ( 26.9 versus 16.7 % ; p=0.30 ) , and neither in the rate of preterm delivery within 48 hours ( 15.4 versus 12.5 % ; p=0.50 ) . Nevertheless , the cephalea rate was significantly higher in the Nitroglycerin Group ( 30.8 versus 8.3 % ; p=0.04 ) . CONCLUSIONS transdermal nitroglycerin has presented similar effectiveness to oral nifedipine to inhibit preterm delivery in the first 48 hours , however with higher cephalea frequency Fig. 1 . Study population . There is a need for an effective tocolytic drug that has fewer side effects than those in use . Ritodrine , a beta adrenergic agonist , is effective up to 48 h after treatment but has no beneficial effects on perinatal mortality and is associated with increased maternal morbidity . Recent studies suggest that glyceryl trinitrate ( GTN ) , a NO donor , may be an effective tocolytic agent w1–4x . We have compared the efficacy and side effects of GTN with ritodrine for the treatment of preterm labor in a r and omized trial conducted at Corniche Hospital , Abu Dhabi , United Arab Emirates , from September 1996 to July 1998 . Women with singleton pregnancies between 23 and 34 weeks ’ gestation with intact amniotic membranes were considered if they presented with painful , regular contractions ( ) 20yh ) documented by external tocography , and yor cervical dilatation of 2 cm or more . Women with known contraindications to tocolysis or known tocolytic exposure during current pregnancy were excluded . Out of 403 women , 132 were r and omly assigned to receive GTN ( ns67 ) or ritodrine ( ns65 ) OBJECTIVE This study was undertaken to assess the effectiveness of glyceryl trinitrate ( GTN ) patches in comparison with beta2 sympathomimetics ( beta2 ) for the treatment of  preterm labor .  STUDY DESIGN A multicenter , multinational , r and omized controlled trial was conducted in tertiary referral teaching hospitals . Women in threatened preterm labor with positive fetal fibronectin or ruptured membranes between 24 and 35 weeks ' gestation were recruited and r and omly assigned to either beta2 or GTN with rescue beta2 tocolysis if moderate-to-strong contractions persisted at 2 hours . Obstetric and neonatal outcomes were assessed . RESULTS Two hundred thirty-eight women were recruited and r and omly assigned , 117 to beta2 and 121 to GTN . On a strict intention-to-treat basis , there was no significant difference in the time to delivery using Kaplan-Meier curves ( P = .451 ) . At 2 hours , 27 % of women receiving beta2 had moderate or stronger contractions compared with 53 % in the GTN group ( P < .001 ) . This led to 35 % of women in the GTN group receiving rescue treatment . If delivery or requirement for beta2 rescue are regarded as treatment failure , then a significant difference was observed between the 2 arms ( P = .0032 ) . There were no significant differences in neonatal outcomes . CONCLUSION GTN is a less efficacious tocolytic compared with ss2 sympathomimetics OBJECTIVE We assessed the ability of maternal plasma corticotropin-releasing hormone measurements to predict preterm delivery in the setting of a pilot study comparing transdermal glyceryl trinitrate with st and ard beta-mimetic therapy for preterm labor and to determine the effect of these tocolytics on maternal plasma corticotropin-releasing hormone concentrations . STUDY DESIGN Twenty-six consecutive patients with preterm labor were r and omized to tocolytic treatment with transdermal glyceryl trinitrate ( n=13 ) or intravenous albuterol ( n=13 ) . RESULTS Plasma corticotropin-releasing hormone immunoreactivity levels were higher in women who were delivered within 7 days ( 41.4+/-13.5 pmol/L ) than in those continuing to term ( 14.2+/-2.4 pmol/L , p=0.011 ) and were not altered by treatment . Two women in each of the treatment groups delivered within 7 days of the initiation of treatment , two women in the glyceryl trinitrate group were changed to albuterol because of persistence of contractions .  Glyceryl trinitrate treatment was associated with significantly fewer maternal side effects . Neither treatment altered umbilical artery Doppler ultrasonographic findings . CONCLUSION Transdermal glyceryl trinitrate is better tolerated than intravenous albuterol but may be no more efficacious than albuterol for the treatment of preterm labor . Biologic markers such as plasma corticotropin-releasing hormone levels may be an important method of identifying women at high risk of preterm delivery In the Obstetrics and Gynaecological Department of the National Research Institute of Mother and Child between January 1998 and December 1998 , sixty women with premature uterine contractions were treated . 30 women were treated using transdermal nitroglicerin ( Nitroderm ) and 30 using Fenoterol . There was no difference between age , parity and gestational age at the beginning of this study . The authors compared the efficiency , tolerance and safety of transdermal nitroglicerin and beta-mimetics used for premature uterine contraction suppression . The frequency and intensity of adverse effects were also evaluated OBJECTIVE The objective of the study was the estimation of the influence of oral supplementation with low-dose l-arginine on feto-placental circulation in women with threatened preterm labor . STUDY DESIGN Oral administration of 3 g of L-arginine daily or placebo as a supplement to st and ard tocolytic therapy was tried in 70 women with threatened preterm delivery , r and omly assigned to the L-arginine ( n=37 ) or placebo ( n=33 ) groups . Twenty-five and 20 completed the study , respectively . Doppler velocimetry of pulsatility indices ( PI ) of the umbilical ( UA ) and middle cerebral ( MCA ) arteries as well as pregnancy outcome and biochemical markers of nitric oxide synthesis ( plasma amino acid and nitrite/nitrate levels , as well as 24 h nitrite/nitrate excretion with urine ) were estimated . RESULTS Starting from the second week of therapy , the UA PI values were significantly lower in the L-arginine group than in the placebo group . Moreover , treatment with L-arginine caused a significant increase in MCA PI and cerebro-placental ratio ( CPR ) values . The changes in feto-placental circulation in the L-arginine group were not associated with any signs of increased nitric oxide synthesis . CONCLUSION Oral supplementation with low doses of L-arginine changed feto-placental blood flow distribution in patients with threatened preterm labor . The exact mechanism of L-arginine action on feto-placental circulation requires further investigation OBJECTIVE This secondary analysis of a r and omized placebo-controlled trial was to hypothesize on mechanisms for the improved neonatal outcomes with the use of nitroglycerin ( GTN ) for preterm labor . STUDY DESIGN Women in the original trial who delivered at term were excluded . A composite of severe neonatal outcomes , gestational age at delivery , and corticosteroid use in addition to Kaplan-Meier survival analysis to assess time from r and omization to delivery were examined . RESULTS A decrease in composite neonatal outcome ( relative risk , 0.21 ; 95 % confidence interval , 0.05 - 0.81 ; P = .018 ) with GTN ( n = 39 ) compared with placebo ( n = 38 ) was primarily due to a 23 day prolongation of pregnancy ( P = .019 ) and a trend ( P = .04 ) toward completing a course of corticosteroids in the subgroup r and omized prior to 28 weeks ' gestation . CONCLUSION We hypothesize that GTN has a gestational age-dependent reduction in neonatal outcomes as a result of pregnancy prolongation and corticosteroid administration OBJECTIVE To evaluate tocolytic efficacy of transdermal glyceryl trinitrate ( GTN ) in comparison to fenoterol per infusionem in a prospect i ve r and omized multicenter study . PATIENTS AND METHODS 50 pregnant women between 27 and 35 weeks of gestation with preterm labour were treated with either GTN patches ( 0.4 - 0.8 mg/h ) or fenoterol per infusionem ( 60 - 120 micrograms/h ) up to stop of contractions or 35 weeks in maximum . The primary outcomes were the prolongation of gestation by 48 h , 7 days or up to 37 weeks of gestation as well as the neonatal outcome . The progression of cervical ripening and maternal side effects during tocolysis were assessed as secondary outcome criteria . RESULTS There was no difference in successful tocolysis for 48 h and 7 days in both groups , whereas significantly more women passed 37 weeks after GTN therapy . So mean duration of pregnancy , birth weight and height were greater , whereas transfer into neonatal care unit was significantly rare after GTN . There 
    Output:
    
Overall , these studies were underpowered to identify differences between groups for most outcomes .When nitric oxide donors were compared with other tocolytic drugs there was no significant evidence that nitric oxide donors performed better than other tocolytics ( betamimetics , magnesium sulphate , a calcium channel blocker or a combination of tocolytics ) in terms of pregnancy prolongation , although nitric oxide donors appeared to be associated with a reduction in most adverse effects , apart from headache .
There was no significant difference between groups for infant morbidity or mortality outcomes .
AUTHORS ' CONCLUSIONS There is currently insufficient evidence to support the routine administration of nitric oxide donors in the treatment of threatened preterm labour