***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 
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    Input: Background Neonatal respiratory distress syndrome , as a consequence of preterm birth , is a major cause of early mortality and morbidity . The withdrawal of progesterone , either actual or functional , is thought to be an antecedent to the onset of labour . There remains limited information on clinical ly relevant health outcomes as to whether vaginal progesterone may be of benefit for pregnant women with a history of a previous preterm birth , who are at high risk of a recurrence . Our primary aim was to assess whether the use of vaginal progesterone pessaries in women with a history of previous spontaneous preterm birth reduced the risk and severity of respiratory distress syndrome in their infants , with secondary aims of examining the effects on other neonatal morbidities and maternal health and assessing the adverse effects of treatment . Methods Women with a live singleton or twin pregnancy between 18 to < 24 weeks ’ gestation and a history of prior preterm birth at less than 37 weeks ’ gestation in the preceding pregnancy , where labour occurred spontaneously or in association with cervical incompetence or following preterm prelabour rupture of the membranes , were eligible . Women were recruited from 39 Australian , New Zeal and , and Canadian maternity hospitals and assigned by r and omisation to  vaginal progesterone pessaries  ( equivalent to 100 mg vaginal progesterone ) ( n = 398 ) or placebo ( n = 389 ) . Participants and investigators were masked to the treatment allocation . The primary outcome was respiratory distress syndrome and severity . Secondary outcomes were other respiratory morbidities ; other adverse neonatal outcomes ; adverse outcomes for the woman , especially related to preterm birth ; and side effects of progesterone treatment . Data were analysed for all the 787 women ( 100 % ) r and omised and their 799 infants . Findings Most women used their allocated study treatment ( 740 women , 94.0 % ) , with median use similar for both study groups ( 51.0 days , interquartile range [ IQR ] 28.0–69.0 , in the progesterone group versus 52.0 days , IQR 27.0–76.0 , in the placebo group ) . The incidence of respiratory distress syndrome was similar in both study groups—10.5 % ( 42/402 ) in the progesterone group and 10.6 % ( 41/388 ) in the placebo group ( adjusted relative risk [ RR ] 0.98 , 95 % confidence interval [ CI ] 0.64–1.49 , p = 0.912)—as was the severity of any neonatal respiratory disease ( adjusted treatment effect 1.02 , 95 % CI 0.69–1.53 , p = 0.905 ) . No differences were seen between study groups for other respiratory morbidities and adverse infant outcomes , including serious infant composite outcome ( 155/406 [ 38.2 % ] in the progesterone group and 152/393 [ 38.7 % ] in the placebo group , adjusted RR 0.98 , 95 % CI 0.82–1.17 , p = 0.798 ) . The proportion of infants born before 37 weeks ’ gestation was similar in both study groups ( 148/406 [ 36.5 % ] in the progesterone group and 146/393 [ 37.2 % ] in the placebo group , adjusted RR 0.97 , 95 % CI 0.81–1.17 , p = 0.765 ) . A similar proportion of women in both study groups had maternal morbidities , especially those related to preterm birth , or experienced side effects of treatment . In 9.9 % ( 39/394 ) of the women in the progesterone group and 7.3 % ( 28/382 ) of the women in the placebo group , treatment was stopped because of side effects ( adjusted RR 1.35 , 95 % CI 0.85–2.15 , p = 0.204 ) . The main limitation of the study was that almost 9 % of the women did not start the medication or forgot to use it 3 or more times a week . Conclusions Our results do not support the use of vaginal progesterone pessaries in women with a history of a previous spontaneous preterm birth to reduce the risk of neonatal respiratory distress syndrome or other neonatal and maternal morbidities related to preterm birth . Individual participant data meta- analysis of the relevant trials may identify specific women for whom vaginal progesterone might be of benefit . Trial registration Current Clinical Trials IS RCT N20269066 OBJECTIVE The aim of this study was to compare perinatal outcomes of patients with second-trimester ultrasonographic evidence of preterm dilatation of the internal os treated with cerclage  versus those of patients not treated with cerclage .  STUDY DESIGN From May 1998 through June 1999 patients with ultrasonographic evidence of preterm dilatation of the internal os between 16 and 24 weeks ' gestation were r and omly assigned to receive a McDonald cerclage or no cerclage .  Before r and om assignment all patients underwent amniocentesis and urogenital cultures and then received 48 hours of therapy with indomethacin and antibiotics . After treatment each patient was followed up as an outpatient with bed rest and weekly ultrasonographic evaluation . RESULTS Of the 61 patients 31 were r and omly assigned to cerclage and 30 were r and omly assigned to no cerclage . There were no differences between groups with respect to maternal demographic characteristics , risk factors for preterm birth , cervical measurements , rescue procedures , readmission , chorioamnionitis , and abruptio placentae . The mean gestational age at delivery ( 33.5 + /- 6.3 weeks ) and the perinatal death rate ( 12 . 9 % ) in the cerclage group were similar to the mean gestational age at delivery ( 34.7 + /- 4.7 weeks ; P = .4 ) and the perinatal death rate ( 10.0 % ; P = .9 ) in the no-cerclage group . CONCLUSION Treatment with McDonald cerclage of preterm dilatation of the cervix detected ultrasonographically during the second trimester did not improve perinatal outcomes Objective . To assess efficacy and tolerability of vaginal compared with intramuscular progesterone in reducing the rate of recurrent  preterm birth before 34 weeks of gestation . Design . Prospect i ve r and omized study . Setting . Obstetrics and Gynecology Department , Armed Forces Hospital Southern Region , Kingdom of Saudi Arabia . Sample . Five‐hundred and eighteen women with a prior history of preterm birth . Methods . Women were r and omized to receive either 90 mg of vaginal progesterone gel once daily or 250 mg of intramuscular progesterone weekly . Treatment began between 14 and 18 weeks of gestation and continued until 36 complete weeks of gestation , delivery or the occurrence of premature rupture of membranes . Main outcome measures . The primary outcome measure was delivery before 34 weeks of gestation . The secondary outcome measures were PTB between 34 and 37 weeks of gestation and neonatal outcomes including birthweight , neonatal death , and the need for admission to the neonatal intensive care unit . Results . The baseline characteristics of the study participants were similar . Two‐hundred and thirty‐eight ( 94.1 % ) patients in the vaginal group and 226 ( 90.8 % ) patients in the intramuscular group were compliant with their medications . Vaginal progesterone was associated with a lower percentage of deliveries before 34 weeks of gestation than the intramuscular preparation ( p= 0.02 ) . This association was also observed at 28 and 32 weeks of gestation ( p= 0.04 ) . Adverse effects were reported in 14.1 % of patients in the intramuscular group , but in only 7.5 % of patients in the vaginal group ( p= 0.017 ) . Conclusions . Vaginal progesterone was more effective than intramuscular progesterone for the prevention of preterm birth and had fewer adverse effects OBJECTIVE To determine the effectiveness of cerclage pessary in the prevention of  preterm birth in asymptomatic Chinese women with a short cervix at 20 to 24 weeks . METHODS Low-risk women carrying singleton pregnancies were screened with transvaginal ultrasound , and those with a cervical length < 25 mm at 20 to 24 weeks were recruited into a r and omized controlled trial , comparing the prophylactic use of cerclage pessary with expectant management . The analysis was by intent-to-treat . The primary outcome measure was preterm delivery before 34 weeks . RESULTS Among 4438 screened women , 203 women ( 4.6 % ) met the inclusion criteria and 108 ( 58 % ) consented for the study . A total of 53 and 55 women were allocated to pessary and control groups , respectively . There was no difference in background demographics , including the mean cervical length ( 19.6 mm versus 20.5 mm ) and the mean gestational age at r and omization ( both 21.9 weeks ) . Delivery before 34 weeks occurred in 9.4 % and 5.5 % ( p = 0.46 ) in the pessary and the control groups , respectively . No differences in major side effects were noted between the groups . CONCLUSION In our population , < 5 % had a cervical length of less than 25 mm at 20 to 24 weeks ' gestation . The prophylactic use of cerclage pessary did not reduce the rate of preterm delivery before 34 weeks Background  Preterm birth is a worldwide health concern due to its various negative consequences . Therefore , the prevention of preterm birth is a top priority for healthcare systems in all countries . Objective To compare the effectiveness of vaginal versus intramuscular progesterone in the prevention of preterm delivery . Methods This r and omized clinical trial was conducted at Shahid Sadoughi Hospital in Yazd , Iran , from November 21 , 2012 to January 20 , 2015 . Seventy-eight pregnant women with singleton pregnancy and one risk factor of preterm delivery were included in the study . The subjects were assigned r and omly to two groups , with group one receiving Cyclogest and group two receiving 17-α hydroxyprogesterone caproate . Subsequently , we analyzed drug complications during pregnancy , delivery time , neonatal outcomes , and patients ’ satisfaction among the two groups . The data were analyzed using SPSS version 16 . We used descriptive statistics , chi-squared , t-test , and ANOVA for the analyses of primary and secondary outcomes . Results Among the 39 births in group one , 33.3 % occurred preterm , and , among the 39 births in group two , 30.7 % occurred preterm ( < 37 weeks ) . The mean gestational ages at delivery in groups 1 and 2 were 37.07 ± 2.23 and 36.81 ± 2.77 weeks , respectively ( p = 0.765 ) . Other variables were not significantly different between the two groups , including birth weight ( p = 0.745 ) , Apgar scores for the first and fifth minutes ( p = 0.574 , 0.630 ) , length of stay in the neonatal intensive care unit ( NICU ) when the newborns needed hospitalization ( p = 0.358 ) , and the patients ’ satisfaction with the drugs that were used ( p = 0.615 ) . Conclusions In this study , vaginal progesterone and intramuscular progesterone  had the same levels of effectiveness , safety and acceptance by patients in the prevention of preterm delivery . Therefore , both can be used for this purpose in clinical practice s , but more studies are needed Background : Preterm birth is the major cause of neonatal mortality and morbidity . Objective : The aim of this study was to evaluate the effect of prophylactic vaginal progesterone on decreasing preterm birth rate and neonatal complications in a high-risk population . Material s and Methods : A r and omized , double-blind , placebo-controlled study was performed on 100 high-risk singleton pregnancies .  Vaginal suppository progesterone ( 400 mg ) or placebo was administered daily between 16 - 22 wks to 36 wks of gestation . Progesterone ( n=50 ) and placebo ( n=50 ) groups were compared for incidence of preterm delivery and neonatal complications . Results : The preterm birth rate was 52 % . Preterm birth rate before the 37 wks of gestation ( 68 % vs. 36 % : RR=1.89 , 95 % CI : 1.25 - 2.86 ) and also before the 34 wks of gestation ( 42 % vs. 18 % : RR=2.33 , 95 % CI : 1.19 - 4.58 ) in placebo group was significantly higher than progesterone group . Our study also showed that the administration of vaginal progesterone was associated with a significant reduction in the risk of birth weight ≤2500 gr , the rates of respiratory distress syndrome ( RDS ) and admission to the Neonatal Intensive Care Unit ( NICU ) in the progesterone group when compared with the placebo group . However , there was no significant difference between the two groups in terms of neonatal death , days of admission in NICU , intra 
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CONCLUSIONS Vaginal progesterone was the only intervention with consistent effectiveness for preventing preterm birth in singleton at-risk pregnancies overall and in those with a previous preterm birth .
TWEETABLE ABSTRACT In up date d NMA , vaginal progesterone consistently reduced PTB in overall at-risk pregnancies and in women with previous PTB