***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: Summary Background The purpose of this study was to compare the obstetric outcome of low-risk maternity patients attended by certified midwives  with that of  low-risk maternity patients attended by obstetricians .  Patients and methods Obstetric outcome of 1352 midwife patients was compared with that of 1352 age- and parity-matched physician patients with normal spontaneous vaginal delivery at the Department of Obstetrics and Gynecology of the University Hospital Vienna during the period from January 1997 to July 2002 . Our analysis was restricted to a sample of low-risk pregnant women . Women with medical or obstetric risk factors were excluded . Results A significant decrease in the use of oxytocin  ( p=0.0001 ) was observed in women who selected a midwife as their primary birth attendant compared with women in the physician group . In both groups most women gave birth in a supine position ; however , significantly more alternative birth positions were used by midwife patients ( p=0.0001 ) . Concerning perineal trauma , a significantly lower rate of episiotomies ( p=0.0001 ) and perineal tears of all degrees ( p=0.006 ) were found in midwife patients . When analyzing severe postpartum hemorrhage and postpartum infections , there were no significant differences between the two groups ( p>0.05 ) . Concerning neonatal outcome , there were no significant differences in APGAR score < 7 at 5 minutes (p>0.05).Our data clearly show the ability of certified midwives to successfully provide prenatal care and delivery to lowrisk maternity patients , with neonatal outcomes comparable to those of physician patients . The use of certified midwives supervised by obstetricians may provide the optimum model for perinatal care , particularly for those women who are low-risk maternity patients , leaving physicians free to attend to the high-risk elements of care OBJECTIVE To review the use of episiotomy during vaginal delivery in Hong Kong public hospitals . DESIGN Prospect i ve observational survey . SETTING Public hospitals , Hong Kong . PARTICIPANTS Women who underwent normal vaginal delivery of a singleton foetus with cephalic presentation . MAIN OUTCOME MEASURES  Number of women having an episiotomy , severe-degree ( third- or fourth-degree ) tear , other types of tear , blood loss at delivery , postpartum haemorrhage , need for blood transfusion , puerperal pyrexia , wound infection , gaping wound that required suture removal , and drainage or resuturing of a perineal wound . RESULTS Between 1 January and 31 March 2003 , there were 6222 singleton spontaneous normal vaginal deliveries in the public hospitals of Hong Kong . Of the 6167 women in whom the status of the perineum was known , episiotomy was performed in 5274 ( 85.5 % ) . Primiparous women were more likely to undergo  episiotomy  at delivery than multiparous women ( 97.9 % vs 71.4 % ) . Women with episiotomy had significantly less perineal tearing of any kind than those without . The occurrence of any type of perineal tear and severe-degree ( third- or fourth-degree ) tear was significantly lower in primiparous women who had an episiotomy than those without ( P<0.05 ) . Women with episiotomy had increased mean blood loss at delivery but other complications were not significantly increased . CONCLUSIONS In Hong Kong , episiotomy is routinely performed during normal vaginal delivery . It is associated with a significantly lower overall rate of perineal tearing . This study was observational , nonetheless the occurrence of other complications was likely to increase when episiotomy was performed . Firm evidence from several r and omised controlled studies shows that routine episiotomy is unjustified and possibly harmful . Routine episiotomy should not be promoted in Hong Kong without further r and omised controlled study OBJECTIVE To analyse the significance of risk factors and the role of episiotomy in preventing  obstetric anal sphincter injury at vaginal delivery . STUDY DESIGN This is a retrospective cross-sectional study in the Norfolk and Norwich University Hospital in the UK . All caesarean sections and non-vertex presentations were excluded , which result ed in a study population of 10,314 deliveries .  Obstetric anal sphincter injury ( OASI ) was defined as third or fourth degree tears to the anal sphincter muscles , with or without a tear involving the anal mucosa . First a univariate analysis was done to identify factors that had a significant association with OASI . Factors included parity , age , gestation , labour induction method , duration of second stage , use of epidural analgesia , episiotomy , method of delivery , time and month of delivery , and birth weight . All factors were then combined in a multivariate logistic regression analysis . The multivariate analysis was then repeated including only factors that had a significant association with OASI in the univariate analysis . Adjusted odds ratios with 95 % confidence intervals ( CI ) were calculated . RESULTS The frequency of anal sphincter lacerations was 3.2 % . There were statistically significant associations between an increased incidence of OASI and parity , birth weight , method of delivery and shoulder dystocia .  Women giving birth without a mediolateral episiotomy were 1.4 times more likely to experience OASI ( 95 % CI 1.021 - 1.983 ) . Interestingly , the incidence of OASI has risen between 2005 and 2007 . CONCLUSION Parity , age , birth weight , method of delivery and shoulder dystocia are strongly associated with obstetric anal sphincter injury .  Mediolateral episiotomy appears to be protective against OASI but a r and omised controlled trial would be needed to confirm this . The rising incidence of OASI after normal vaginal deliveries may be related to adoption of the h and s off technique or increased identification of tears Episiotomy is a widely-done intervention in childbirth , regardless of poor scientific evidence of its benefits . This r and omised controlled trial compares selective with routine use of a mediolateral episiotomy for women having first and second deliveries in 8 public maternity units in Argentina . 2606 women participated ; 1555 were nulliparous ( 778 in the selective group and 777 in the routine group ) and 1051 primiparous ( 520 in the selective group and 531 in the routine group ) . The two interventions compared were selective ( limited to specified maternal or fetal indications ) , and routine episiotomy ( following the hospital 's previous policy ) . Episiotomy was done in 30.1 % of deliveries in the selective , and 82.6 % in the routine group . The main outcome measure was severe perineal trauma . Severe perineal trauma was uncommon in both groups but was slightly less frequent in the selective group ( 1.2 % vs 1.5 % ) . Anterior perineal trauma was more common in the selective group but posterior perineal surgical repair , perineal pain , healing complications , and dehiscence were all less frequent in the selective group . Routine  episiotomy should be ab and oned and episiotomy rates above 30 % can not be justified BACKGROUND Anal incontinence is an embarrassing condition that is largely underreported . Obstetric anal sphincter injuries are the major etiological factor . Recognition of risk factors may minimize the development of sphincter injuries . The objective of this study was to identify risk factors for sphincter injuries and measure dimensions of mediolateral episiotomies . METHODS Women expecting their first vaginal delivery were invited to participate , and an experienced research fellow performed a perineal and rectal examination and classified tears according to the new international classification . Dimensions of episiotomies were measured and obstetric variables recorded prospect ively . RESULTS Of the 241 women recruited , 59 ( 25 % ) sustained sphincter injuries .  Univariate analysis revealed that forceps delivery OR 4.03 ( 1.63 - 9.92 ) , vacuum extraction OR 2.64 ( 1.25 - 5.54 ) , gestation > 40 weeks OR 3.18 ( 2.35 - 4.29 ) , and mediolateral episiotomy OR 5.0 ( 2.64 - 9.44 ) were associated with these injuries . In addition , compared with women who had no injuries , sphincter injuries were more common with higher birthweight ( 3.51 vs 3.17 kg , p < 0.01 ) , larger head circumference ( 34.3 vs 33.3 cm , p < 0.01 ) , and longer second stage of labor ( 76 vs 51 min , p < 0.01 ) . Multiple logistic regression revealed higher birthweight and mediolateral episiotomy OR 4.04 ( 1.71 - 9.56 ) as independent risk factors .  Episiotomies  angled closer to the midline were significantly associated with such injuries ( 26 vs 37 degrees , p = 0.01 ) . No midwife and only 13 ( 22 % ) doctors performed truly mediolateral episiotomies . CONCLUSIONS Mediolateral episiotomy is an independent risk factor for anal sphincter injuries . Although a liberal policy of mediolateral episiotomy does not appear to reduce the risk of such injuries , it may be related to inappropriate technique . A concerted approach to educate trainees in appropriate episiotomy technique and identification of sphincter injuries is imperative to enable reexamination of the true merits or disadvantages of mediolateral episiotomy OBJECTIVE To study the angle of mediolateral episiotomy at the time of cut , after primary repair , and 6 months postpartum ; and the incidence and severity of perineal pain and anal incontinence 6 months after delivery . METHODS The study group comprised 60 consecutively recruited primiparous women who required episiotomy during delivery assisted by 2 obstetricians . The incision angle of episiotomy ( defined as 60 ° ) was measured before cutting , after primary repair , and after 6 months . At follow-up , perineal pain was evaluated by a verbal rating score ; anal incontinence was assessed by St Mark 's score . RESULTS The angles differed significantly among the incision ( 60 ° ) , repair ( 45 ° ) , and 6-month ( 48 ° ) measurements ( P < 0.001 ) . There was a poor correlation between the suture angle and the angle measured at 6 months postpartum . No severe perineal tear was diagnosed in the cohort . At 6 months postpartum , only 1 woman reported mild symptoms of de novo anal incontinence , whereas 7 women reported perineal pain related to episiotomy . CONCLUSION An incision angle of mediolateral episiotomy of 60 ° result ed in a low incidence of anal sphincter tearing , anal incontinence and perineal pain . A r and omized controlled trial is needed to assess the outcome when different angles of episiotomy are used OBJECTIVE : To evaluate the effect of mediolateral episiotomy on puerperal pelvic floor strength and dysfunction ( urinary and anal incontinence , genital prolapse ) . METHODS : Five hundred nineteen primiparous women were enrolled 3 months after vaginal delivery . Puerperae were divided in 2 groups : group A ( 254 women ) comprised the women who received mediolateral episiotomy  and group B ( 265 women ) the women with intact perineum and first- and second-degree spontaneous perineal lacerations . Each woman was question ed about urogynecological symptoms and examined by digital test , vaginal perineometry , and uroflowmetric stop test score . Data were subjected to Student t test and Fisher exact test to assess , respectively , the difference between the mean values and the proportions within the sub population s. Using a simple logistic regression model to test an estimate of relative risk , we expressed the odds ratios of the variables considered with respect to the control population ( group B ) . RESULTS : No significant difference was found with regard to the incidence of urinary and anal incontinence and genital prolapse , whereas dyspareunia and perineal pain were significantly higher in the episiotomy group ( 7.9 % versus 3.4 % , P = .026 ; 6.7 % versus 2.3 % , P = .014 , respectively ) . Episiotomy was associated with significantly lower values , both in digital test ( 2.2 versus 2.6 ; P < .001 ) and in vaginal manometry ( 12.2 versus 13.8 cm water ; P < .001 ) , but not in uroflowmetric stop test . CONCLUSION : Mediolateral episiotomy does not protect against urinary and anal incontinence and genital prolapse and is associated with a lower pelvic floor muscle strength compared with spontaneous perineal lacerations and with more dyspareunia and perineal pain . LEVEL OF EVIDENCE : 
    Output:
    
Conclusion The pooled analysis of a large number of women undergoing vaginal birth , most of who were nulliparous , indicates that MLE has a beneficial effect in prevention of OASI .
An accurately given MLE might have a role in reducing OASI and should not be withheld , especially in nulliparous women .