***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 Infants born very preterm ( <33 weeks ) are at increased risk of neurocognitive deficits . Their neurodevelopmental outcome up to age 8 years can be predicted by neonatal ultrasonography , but little is known of their later function . We investigated the effect of very preterm birth on brain structure and neurocognitive and behavioural functioning in adolescence . METHODS A cohort of 105 infants born before 33 weeks of gestation in 1979 - 80 had ultrasonographic scans at University College Hospital , London , and were prospect ively examined at 1 , 4 , and 8 years . At age 14 - 15 years , 72 of those who remained in UK ( cases ) and 21 age-matched full-term controls underwent brain magnetic resonance imaging ( MRI ) , as well as neurological , cognitive , and behavioural assessment . MRI images were assessed by two neuroradiologists unaware of ultrasonographic findings or case or control status . FINDINGS Of the 72 cases , 40 had unequivocally abnormal MRI and 15 had equivocal scans . Of the 21 controls , one had abnormal and five equivocal MRI . Abnormalities of ventricles , corpus callosum , and white matter were especially common in cases . More brain lesions were identified by MRI than by neonatal ultrasonography . The cases had significantly more reading , adjustment , and neurological impairments than controls , but their behaviour was significantly related to MRI abnormality . INTERPRETATION Individuals born very preterm show an excess of neurocognitive and behavioural problems in adolescence , and more than half have abnormal MRI brain scans OBJECTIVE To assess whether cervical cerclage in women deemed to be at increased risk of cervical incompetence prolongs pregnancy and thereby improves fetal and neonatal outcome . DESIGN Multicentre r and omised controlled trial . SETTING Hospitals in the United Kingdom , France , Hungary , Norway , Italy , Belgium , Zimbabwe , South Africa , Icel and , Irel and , the Netherl and s and Canada . SUBJECTS One thous and two hundred and ninety-two pregnant women whose obstetricians were uncertain whether to recommend cervical cerclage , most of whom had a history of early delivery or cervical surgery . INTERVENTIONS Cervical cerclage was compared with a policy of withholding the operation unless it was considered to be clearly indicated . MAIN OUTCOME MEASURES Delivery before 33 completed weeks , preterm delivery ( < 37 weeks ) , and vital status of the baby after completion of the pregnancy . RESULTS The overall preterm delivery rate was 28 % . There were fewer deliveries before 33 weeks in the cerclage group ( 83 ( 13 % ) compared with 110 ( 17 % ) , P = 0.03 ) and this difference reflected deliveries characterised by features of cervical incompetence ( painless cervical dilatation and prelabour rupture of the membranes ) . There was a corresponding difference in very low birthweight deliveries ( 63 ( 10 % ) compared with 86 ( 13 % ) , P = 0.05 ) . The difference in the overall rate of miscarriage , stillbirth or neonatal death ( 55 ( 9 % ) compared with 68 ( 11 % ) ) was less marked and was not statistically significant . The use of cervical cerclage was associated with increased medical intervention and a doubling of the risk of puerperal pyrexia . CONCLUSIONS These results suggest that the operation had an important beneficial effect in 1 in 25 cases in the trial ( 95 % confidence interval ( CI ) 1 in 12 to 1 in 300 sutures ) . Its use is associated with increased medical intervention and puerperal pyrexia . Nevertheless , this trial suggests that , on balance , cervical cerclage should be offered to women at high risk , such as those with a history of three or more pregnancies ending before 37 weeks gestation Objective : The aim of the present study was to compare the outcome of pregnancies among patients with suspected cervical incompetence treated either by elective cervical cerclage or an alternative management program involving cervical surveillance To determine the value of transvaginal sonography in women with a previous history of second trimester miscarriage due to cervical incompetence , 55 patients were subjected to either elective cervical cerclage or follow-up  ( every second patient ) with weekly evaluations of the cervix by transvaginal ultrasonography . Emergency cerclage was applied when significant cervical changes were noted . All patients were evaluated with cervical cultures and ultrasound .  Women with infection , fibroids , uterine malformations and multiple pregnancies were excluded from the study . The study population was divided in two groups . In group I ( n=27 ) elective cerclage was applied during the 14th week . Women in group II ( n=28 ) were subjected to serial weekly evaluations of the cervix by transvaginal ultrasonograms . In 18 cases emergency cerclage was applied due to significant cervical changes . In group I , labor started before the 33rd week in two cases ( 7.4 % ) , between 33 and 37 weeks in nine ( 33.3 % ) and after the 37th week in 16 cases ( 59.2 % ) . Out of the 18 patients in group II who had cervical cerclage after ultrasonographic evaluation , four ( 22.2 % ) delivered before the 33rd week , three ( 16.6 % ) between 33 and 37 weeks and 11 ( 61.1 % ) after the 37th week . No statistical difference was noted between the two groups referring to pregnancy outcome ( p<0.1 ) . We concluded that ultrasound-guided management despite cervical shortening , does not result in unfavorable pregnancy outcome . A significant number of patients can avoid the operation OBJECTIVE The objective of this study was to compare different management strategies for women at risk for cervical incompetence . STUDY DESIGN In an ongoing r and omized trial patients with a previous preterm delivery at < 34 weeks ' gestation who met clinical criteria for the diagnosis of cervical incompetence are allocated to receive a prophylactic cerclage ( prophylactic cerclage group ) or not ( observational group ) in a proportion of 1:2 . Transvaginal ultrasonographic follow-up examination of the cervix is performed in both groups . When a patient of the latter group has a cervical length < 25 mm at < 27 weeks ' gestation , a further r and om assignment of therapeutic cerclage or no cerclage is performed . The analysis is by intent to treat . RESULTS Primary r and om assignment allocated 23 women to the prophylactic cerclage group and 44 to the observational group . Both groups were comparable with respect to obstetric history . No significant difference was found between the prophylactic cerclage group and the observational group in preterm delivery at < 34 weeks ' gestation ( 3/23 vs 6/44 , respectively ) and neonatal survival ( 21/23 vs 41/44 , respectively ) . A cervical length < 25 mm was found in 18 patients ( 41 % ) in the observational group at a mean gestational age of 19.1 + /- 2.9 weeks ' gestation . Incidence of preterm delivery at < 34 weeks ' gestation was significantly higher in the group with short cervical length ( 6/18 vs 0/26 ; P = .003 ) . Secondary r and om assignment of the 18 patients with short cervical length allocated 10 to undergo therapeutic cerclage . Preterm delivery at < 34 weeks ' gestation was significantly less frequent in the therapeutic cerclage group ( 1/10 vs 5/8 ) . CONCLUSION Transvaginal ultrasonographic serial follow-up examinations of the cervix in women at risk for cervical incompetence , with secondary intervention as indicated , appears to be a safe alternative to the traditional prophylactic cerclage . Transvaginal ultrasonographic follow-up examination of the cervix can save the majority of women from unnecessary intervention . Placement of a therapeutic cerclage may reduce the incidence of preterm delivery at < 34 weeks ' gestation among high-risk patients BACKGROUND The role of the cervix in the pathogenesis of  premature delivery  is controversial . In a prospect i ve , multicenter study of pregnant women , we used vaginal ultrasonography to measure the length of the cervix ; we also documented the incidence of spontaneous delivery before 35 weeks ' gestation . METHODS At 10 university-affiliated prenatal clinics , we performed vaginal ultrasonography at approximately 24 and 28 weeks of gestation in women with singleton pregnancies . We then assessed the relation between the length of the cervix and the risk of spontaneous preterm delivery . RESULTS We examined 2915 women at approximately 24 weeks of gestation and 2531 of these women again at approximately 28 weeks .  Spontaneous preterm delivery ( at less than 35 weeks ) occurred in 126 of the women ( 4.3 percent ) examined at 24 weeks . The length of the cervix was normally distributed at 24 and 28 weeks ( mean [ + /- SD ] , 35.2 + /- 8.3 mm and 33.7 + /- 8.5 mm , respectively ) . The relative risk of preterm delivery increased as the length of the cervix decreased . When women with shorter cervixes at 24 weeks were compared with women with values above the 75th percentile , the relative risks of preterm delivery among the women with shorter cervixes were as follows : 1.98 for cervical lengths at or below the 75th percentile ( 40 mm ) , 2.35 for lengths at or below the 50th percentile ( 35 mm ) , 3.79 for lengths at or below the 25th percentile ( 30 mm ) , 6.19 for lengths at or below the 10th percentile ( 26 mm ) , 9.49 for lengths at or below the 5th percentile ( 22 mm ) , and 13.99 for lengths at or below the 1st percentile ( 13 mm ) ( P < 0.001 for values at or below the 50th percentile ; P = 0.008 for values at or below the 75th percentile ) . For the lengths measured at 28 weeks , the corresponding relative risks were 2.80 , 3.52 , 5.39 , 9.57 , 13.88 , and 24.94 ( P < 0.001 for values at or below the 50th percentile ; P = 0.003 for values at the 75th percentile ) . CONCLUSIONS The risk of spontaneous preterm delivery is increased in women who are found to have a short cervix by vaginal ultrasonography during pregnancy OBJECTIVE To compare pregnancy outcome for women at risk of preterm delivery undergoing elective cervical cerclage in the first trimester or serial transvaginal assessment of cervical length with  cerclage only if indicated ( control cases ) . DESIGN A matched case control study . SETTING Prematurity clinic at two London teaching hospitals . POPULATION Women at high risk for preterm delivery . METHODS Cases of  elective cervical cerclage were matched for maternal age , ethnic group , previous cervical surgery , previous second trimester loss and early preterm delivery to women undergoing serial ultrasound surveillance of cervical length . Pregnancy outcome data was collected . Data was analysed using Fisher 's exact , Mann-Whitney and Student 's t-tests . MAIN OUTCOME MEASURES Gestation at delivery , rate of delivery < 24 , 24 - 32 and 32 - 37 weeks gestation . RESULTS Thirty-nine cases of elective cervical cerclage were matched to control cases . Both groups were similar for maternal age , ethnic group , previous cervical surgery , previous second trimester loss and early preterm delivery . Cervical cerclage was performed in 14 ( 36 % ) of the control cases due to cervical changes . There was no significant difference in median gestation at delivery ( 266 days versus 260 days P=0.9 ) , number delivering < 24 weeks ( 15 % versus 13 % P=0.9 ) , at 24 - 32 weeks ( 7.5 % versus 15 % P=0.6 ) and at 32 - 37 weeks ( 15 % versus 13 % P=0.9 ) . CONCLUSION Serial transvaginal ultrasound surveillance of cervical length in women at high risk of preterm delivery appears to reduce cerclage rates without compromising pregnancy outcome . A large multicentered r and omised trial is required to confirm these findings Summary . A total of 506 women at moderate risk of preterm delivery were r and omly allocated to either cervical cerclage or a control group . Significantly more women in the group allocated to cerclage were admitted to hospital for reasons other than the operation and more received oral toco‐lytic drugs . There were also more caesarean sections and more preterm deliveries in the women allocated to cerclage although the differences between the two groups were small and not statistically significant 
    Output:
    
In conclusion , using ultrasound to identify women at risk of cervical insufficiency because of a history of PTD reduces cerclage rates and results in similar pregnancy outcomes as cerclage placement on the basis of history alone .