Perineal injuries and birth positions among 2992 women with a low risk pregnancy who opted for a homebirth
© The Author(s). 2016
Received: 7 February 2016
Accepted: 23 July 2016
Published: 29 July 2016
Whether certain birth positions are associated with perineal injuries and severe perineal trauma (SPT) is still unclear. The objective of this study was to describe the prevalence of perineal injuries of different severity in a low-risk population of women who planned to give birth at home and to compare the prevalence of perineal injuries, SPT and episiotomy in different birth positions in four Nordic countries.
A population-based prospective cohort study of planned home births in four Nordic countries. To assess medical outcomes a questionnaire completed after birth by the attending midwife was used. Descriptive statistics, bivariate analysis and logistic regression were used to analyze the data.
Two thousand nine hundred ninety-two women with planned home births, who birthed spontaneously at home or after transfer to hospital, between 2008 and 2013 were included. The prevalence of SPT was 0.7 % and the prevalence of episiotomy was 1.0 %. There were differences between the countries regarding all maternal characteristics. No association between flexible sacrum positions and sutured perineal injuries was found (OR 1.02; 95 % CI 0.86–1.21) or SPT (OR 0.68; CI 95 % 0.26–1.79). Flexible sacrum positions were associated with fewer episiotomies (OR 0.20; CI 95 % 0.10–0.54).
A low prevalence of SPT and episiotomy was found among women opting for a home birth in four Nordic countries. Women used a variety of birth positions and a majority gave birth in flexible sacrum positions. No associations were found between flexible sacrum positions and SPT. Flexible sacrum positions were associated with fewer episiotomies.
KeywordsHome birth Birth positions Severe perineal trauma Perineal injuries Episiotomy Waterbirth
Perineal injuries and severe perineal trauma involving the anal sphincter complex (SPT) are associated with short- and long-term morbidity, such as perineal pain [1, 2], dyspareunia [2, 3] and anal incontinence . Both short- and long-term symptoms have an impact on women’s daily lives  and on women’s quality of life for those with persistent defects . The prevalence of perineal injuries of all types is reported to be 77–86 % [7, 8] of which 60 % need to be sutured . The incidence of SPT in the Nordic countries (in this article ‘Nordic countries’ refers to Norway, Sweden, Denmark and Iceland) varies from 2.3 % in Norway to 4.2 % in Denmark [9–11] whereas there is no national data available regarding the prevalence of less severe injuries.
Known risk factors for perineal trauma, including SPT are primiparity [12, 13], high birth weight  and occiput posterior presentation . Obstetrical factors associated with SPT are a prolonged second stage [12, 15], instrumental delivery , episiotomy , poor visualization of the perineum , fundal pressure , the lithotomy position  and oxytocin augmentation . Few studies have assessed risk factors for less severe perineal trauma such as second degree tears but the risk factors appears to be similar . Home births have been associated with fewer perineal injuries and SPT compared to hospital births [21–23].
Women who choose home birth are a selected and highly motivated population. Generally they are multiparous, are older, and tend to have a higher socioeconomic status . Fewer are smokers and overweight, which can be viewed as indicators of health . The prevalence of planned home birth varies in the Nordic countries. In Sweden and Norway it is 0.06 % and 0.019 % respectively, while home birth is more common in Denmark and Iceland with 1.5–1.8 % . It is not known whether the observed benefit of opting for a home birth with regard to SPT and perineal injuries is due to differences in midwifery practice, the selected population of women or other factors, such as birth position. Midwifery care measures at home to prevent perineal injuries include getting to know the woman before the onset of labor, following the physiological process of birth and letting her choose the position for birth . Furthermore some of the obstetrical risk factors of SPT are not present in the home birth setting, such as instrumental delivery, the lithotomy position for birth, and oxytocin augmentation since the woman will be transferred to hospital in the event of an emergency or slow progress of labor. Waterbirth on the other hand is common in this setting ; in some studies it is associated with SPT and perineal injuries [23, 29] but not in others .
There is still controversy around whether upright or recumbent birth positions are beneficial or harmful with regard to SPT as well as less severe perineal injuries. Giving birth in the lateral and all-fours position has been associated with a higher prevalence of intact perineum [31–33] but this is not found in the meta-analysis by Gupta et al. . Upright birth positions occur more often within certain birth settings, such as birth centers and at home . Upright birth positions in Western obstetrics may be defined as positions in which a line connecting the center of a woman’s third and fifth vertebrae is more vertical than horizontal [34, 35]. According to this definition sitting, squatting, the birth-seat, kneeling and standing are defined as upright positions, whereas lateral and all-fours, semi-recumbent and the lithotomy position are considered supine positions , although they are different and may facilitate or hinder physiological birth.
Another possible definition is to classify birth positions in which the body weight is on or off the sacrum. Positions that take the weight off the sacrum and allow the pelvic outlet to expand might be favorable to facilitating spontaneous birth . Birth positions that take the weight off the sacrum and could be categorized as flexible sacrum positions are kneeling, standing, all-fours, lateral position, squatting and giving birth on the birth seat. On the other hand all the positions where the woman is sitting or lying on her back, such as the supine and the semi-recumbent position put weight on the sacrum and could be categorized as non-flexible sacrum positions. The evidence as to the impact of upright birth and flexible sacrum positions on perineal outcomes remains inconclusive  and has to our knowledge not been tested in the home birth setting. Since home births are seldom recorded in the registers in the Nordic countries, the prevalence of perineal injuries, SPT, episiotomy and birth positions for women opting for a home birth is not known.
The objective of this study is to describe the prevalence of perineal injuries of different severity in a low-risk population of women who planned to give birth at home in four Nordic countries and to compare the prevalence of perineal injuries, SPT and episiotomy in flexible and non-flexible birth positions.
Design and study sample
This is a prospective cohort study collecting data from planned home births in Norway, Denmark, Sweden and Iceland between 2008 and 2013. All midwives attending home births were asked to recruit their clients to the study. The women were given information about the study during pregnancy, and signed a form agreeing to participate. The method and data collection has been described previously by Blix et al. 
The data collection lasted from January 1st 2008 to December 31st 2012 in Norway, in Sweden from January 1st 2009 to December 31st 2013, in Denmark from March 1st 2010 to May 15th 2013 and in Iceland from January 1st 2010 to December 31st 2013.
N = 2992
N = 468
N = 438
N = 1799
N = 287
Number of children
One previous child
Two previous children
Three or more previous children
Body Mass Index (BMI), mean (SD)
Descriptive statistics, Chi2 and ANOVA tests were used to present the background characteristics and compare data between the Nordic countries. The outcome variables were sutured perineal and vaginal injuries, SPT, episiotomies and total posterior trauma. Crude and adjusted odds ratios with a 95 % confidence interval were calculated between the outcome variables and flexible sacrum positions. Potential confounders were adjusted for using logistic regression. The IBM SPSS software package version 22.0 was employed for the data analysis.
For the purpose of this study, a selected sample of 2992 of the original cohort of 3068 women with a planned home birth was included. A total of 76 women who had a caesarean section or an instrumental delivery after transfer to hospital were excluded. Instrumental deliveries were excluded since they are performed in a supine or recumbent birth position. Of the 2992 women, 2796 (93.4 %) successfully gave birth at home and 196 (6.6 %) gave birth spontaneously after transfer to the hospital. The most common reason for transfer was slow progress of labor.
Table 1 shows the background characteristics of the 2992 women included in this study. The majority of the planned home births in this study occurred in Denmark (n = 1799), followed by Norway (n = 468), Sweden (n = 438) and Iceland (n = 287). The mean age for the total sample was 32 years (range 18–47). There were significant differences between the countries regarding all maternal characteristics. The Icelandic mothers were the youngest and the Swedish mothers were the oldest. The highest proportion of planned home births for women expecting their first baby occurred in Iceland (21.7 %) and in Denmark (18.5 %). Most women irrespective of country were married or cohabiting, did not smoke and were expecting their second baby. Among the multiparous women in the cohort, 140 (4.7 %) women attempted a planned home birth after a caesarean section (VBAC). The vast majority (85 %) of these planned VBAC home births occurred in Denmark.
N = 2992
N = 524
N = 2422
N = 46 (1.5)
Total perineal injury
Birth positions, waterbirth and flexible sacrum positions stratified by parity
N = 2992
N = 524
N = 2422
N = 46 (1.5)
Risk factors for different types of perineal trauma
Total perineal trauma
Birthweight > 4000 g d
Transfer before birth
Flexible sacrum positionse
The major finding of this study is a low prevalence of SPT and episiotomy which did not differ between the countries. The women in this cohort used a variety of birth positions and one third of them gave birth in water. No association was found between flexible sacrum positions and SPT or sutured injuries. Episiotomy was associated with giving birth in a non-flexible sacrum position.
The prevalence of SPT and episiotomy in this study is in line with previous research [21, 24, 38] and adds to the growing body of evidence regarding positive maternal outcomes and low levels of intervention for women with low risk choosing to give birth outside the hospital. Furthermore, the prevalence of SPT and episiotomy in this study did not differ between the countries, which is interesting considering the observed differences between the Nordic countries (2.3 to 4.2 %) [9–11]. Stating what prevalence of SPT should be considered to indicate good quality of care is problematic and has been discussed . A low prevalence of SPT could be due to successful interventions during the second stage. On the other hand when midwives and obstetricians focus on assessment and classifying perineal injuries, the detection rate of SPT often increases [39, 40]. A prevalence between 1.0 and 3.9 % has been suggested to be a realistic target in high-risk units  but what rate is reasonable in a low-risk setting is not known. A lower prevalence of SPT could be expected in a low-risk setting such as home birth where fewer of the obstetrical interventions associated with SPT are present. Stedenfeldt et al. (2014) have shown that the greatest reduction in sphincter injuries after an educational program for midwives and obstetricians took place among low risk-births (i.e., second child, birth weight <4000 g and spontaneous birth with the baby in the occiput anterior position) .
The women in this study used a variety of birth positions and the majority used flexible sacrum positions. A recent review of the literature reports physical and psychological benefits for women when they give birth in an upright position of their choice  but the position assumed by women during birth is influenced by several complex factors. Upright birth positions occur more often within certain birth settings, such as birth centers and home [28, 29]. The midwife’s preference  as well as cultural values may influence the position for birth [34, 42]. It is not possible in this study to determine whether midwives influenced the position for birth but the variation in positions used suggests that women had the opportunity to choose position themselves. Although the number of SPT in this study was low, with only 21 detected cases, no generalizations can be drawn. However, none of the birth positions used – supine, upright or flexible sacrum positions – was associated with SPT which is in line with meta-analyses of the subject . This indicates that midwives were skilled in attending women in different birth positions and it is also in line with the current evidence suggesting that women should be encouraged to give birth in the position most comfortable for them .
Flexible sacrum positions were associated with fewer episiotomies. To our knowledge and according to the midwifery literature [44, 45], midwives are taught to perform an episiotomy in the lithotomy or semi-recumbent position. This could imply that this finding is confounded by indication. If a midwife finds it necessary to perform an episiotomy, she will ask the woman to change position from a flexible sacrum position to a non-flexible sacrum position (semi-recumbent or supine). However, when looking at which birth position women had when the episiotomy was cut, 9 (30.0 %) of the 30 episiotomies were performed in a position other than the semi-recumbent or supine: 7 in the lateral position, 1 in squatting and 1 in the all-fours position. Five of the episiotomies were performed in water.
One limitation of this study is the lack of information regarding midwifery practices during the second stage to prevent perineal injuries, as well as midwives’ experience and training in assessing and suturing perineal injuries. There is evidence that perineal injuries are often misclassified  by both midwives and obstetricians. A second examiner and educational workshops have been shown to improve diagnosis and the appropriate classification of perineal trauma [46, 47]. Information regarding whether a rectal examination has been performed would be of value in further studies.
Another limitation is that midwives in four different countries entered the data. However, using the same protocol limits the classification bias. Midwives who assist women at home births are usually employed within the health care system and are used to recording this type of data, which is similar to the data entered in hospital records. The strength of this study is that the majority of women opting for a home birth and all the midwives assisting with home births on a regular basis in Norway, Sweden, Denmark and Iceland were identified and agreed to participate in this study. According to Blix et al.  the original cohort of 3068 women is suggested to cover 80–90 % of the planned home births in the four Nordic countries.
It is important to evaluate perineal outcome in relation to birth setting, since perineal injuries are associated with short- and long-term morbidity for women . Home births in Norway, Sweden, Denmark and Iceland are not always registered and it is not possible to access the data specific to this study from the medical birth registers. The population studied consists of healthy women, giving birth without many of the interventions associated with modern obstetrics. Further studies are needed to assess long-term consequences of childbirth, such as urinary incontinence, dyspareunia, anal incontinence and the prevalence of prolapse in women giving birth at home. It would be of interest to study the impact of physiological birth on the pelvic floor in this group of women since they receive low levels of obstetric interventions.
A low prevalence of SPT and episiotomy was found among women opting for a home birth in four Nordic countries. Women used a variety of birth positions and a majority gave birth in flexible sacrum positions. No associations were found between flexible sacrum position and SPT. Further studies are needed to assess the long-term consequences related to perineal injuries for women giving birth at home.
The authors want to thank all the women who participated in this study, and Anette S. Huitfeldt and Ásrún Ösp Jónsdottir for collecting data in Norway and Iceland.
Avaliability of the dataset: Please contact the corresponding author.
The study was funded by the Northern Norway Regional Health Authority, the Swedish Council for Working Life and Social Research, the Danish Association of Midwives’ Research Fund, Aase and Ejnar Danielsen’s Fund, Denmark, the Icelandic Association of Midwives’ Research Fund and Oslo and Akershus University College for Applied Sciences, Norway.
HL, EB and ÓÁÓ initiated and designed the study together with Hanne Kjærgaard, who passed away in December 2013. KI, HL, EB and ÓÁÓ carried out the data collection. ME analyzed the data and wrote the manuscript. ME, HL, IH, EB, HKH, ÓÁÓ, MM and KI participated in interpretation of results and participated in the writing process. ME, HL, IH, EB, HKH, ÓÁÓ, MM and KI read and approved the final manuscript.
The authors declare that they have no competing interests.
The study was approved separately in each of the participating countries, by the Regional Committee for Medical and Health Research Ethics (REC North) (200704605–5) in Norway, by the Regional Committee at Karolinska Institutet (2009/147-31) in Sweden, by The Capital Region Committee on Health Research Ethics (H-3-2014-FSP71) in Denmark, and by The National Bioethics Committee (No. 11–031) in Iceland. All women participating in this study were given written information and consented to participate. They were informed of the possibility to withdraw their consent at any time without any consequences regarding care during pregnancy, birth and the postnatal period.
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- Macarthur AJ, Macarthur C. Incidence, severity, and determinants of perineal pain after vaginal delivery: a prospective cohort study. Am J Obstet Gynecol. 2004;191(4):1199–204.View ArticlePubMedGoogle Scholar
- Schytt E, Lindmark G, Waldenstrom U. Physical symptoms after childbirth: prevalence and associations with self-rated health. BJOG. 2005;112(2):210–7.View ArticlePubMedGoogle Scholar
- Rathfisch G, Dikencik BK, Kizilkaya Beji N, Comert N, Tekirdag AI, Kadioglu A. Effects of perineal trauma on postpartum sexual function. J Adv Nurs. 2010;66(12):2640–9.View ArticlePubMedGoogle Scholar
- Sultan AH, Kamm MA, Hudson CN, Bartram CI. Third degree obstetric anal sphincter tears: risk factors and outcome of primary repair. BMJ (Clinical research ed). 1994;308(6933):887–91.View ArticleGoogle Scholar
- Way S. A qualitative study exploring women's personal experiences of their perineum after childbirth: expectations, reality and returning to normality. Midwifery. 2012;28(5):e712–9.View ArticlePubMedGoogle Scholar
- Reid AJ, Beggs AD, Sultan AH, Roos AM, Thakar R. Outcome of repair of obstetric anal sphincter injuries after three years. Int J Gynaecol Obstet. 2014;127(1):47–50.View ArticlePubMedPubMed CentralGoogle Scholar
- Albers LL, Sedler KD, Bedrick EJ, Teaf D, Peralta P. Midwifery care measures in the second stage of labor and reduction of genital tract trauma at birth: a randomized trial. J Midwifery Womens Health. 2005;50(5):365–72.View ArticlePubMedPubMed CentralGoogle Scholar
- McCandlish R, Bowler U, van Asten H, Berridge G, Winter C, Sames L, Garcia J, Renfrew M, Elbourne D. A randomised controlled trial of care of the perineum during second stage of normal labour. Br J Obstet Gynaecol. 1998;105(12):1262–72.View ArticlePubMedGoogle Scholar
- Laine K, Rotvold W, Staff AC. Are obstetric anal sphincter ruptures preventable?-- large and consistent rupture rate variations between the Nordic countries and between delivery units in Norway. Acta Obstet Gynecol Scand. 2013;92(1):94–100.View ArticlePubMedGoogle Scholar
- National Board of health and Welfare. Graviditeter, förlossningar och nyfödda barn. Medicinska födelseregistret 1973–2014. (National data from the Swedish Birthregister - annual report 1973–2014), vol. 2016. Welfare NBoha; 2015. http://www.socialstyrelsen.se/publikationer2015/2015-12-27Google Scholar
- Bjarnadottir RG, Smárason AK, Pálsson GI. Faedingarskráningunni fyrir árid 2013. (Report from the Icelandic Birth Registry for 2013), vol. 2016. National Hospital of Iceland R; 2013. http://www.landspitali.is/library/Sameiginlegar-skrar/Gagnasafn/Rit-og-skyrslur/Faedingaskraningar/faedingarskraning_skyrsla_2013.pdf.Google Scholar
- de Leeuw JW, Struijk PC, Vierhout ME, Wallenburg HC. Risk factors for third degree perineal ruptures during delivery. BJOG. 2001;108(4):383–7.PubMedGoogle Scholar
- Elfaghi I, Johansson-Ernste B, Rydhstroem H. Rupture of the sphincter ani: the recurrence rate in second delivery. BJOG. 2004;111(12):1361–4.View ArticlePubMedGoogle Scholar
- Raisanen SH, Vehvilainen-Julkunen K, Gissler M, Heinonen S. Lateral episiotomy protects primiparous but not multiparous women from obstetric anal sphincter rupture. Acta Obstet Gynecol Scand. 2009;88(12):1365–72.View ArticlePubMedGoogle Scholar
- Valsky DV, Lipschuetz M, Bord A, Eldar I, Messing B, Hochner-Celnikier D, Lavy Y, Cohen SM, Yagel S. Fetal head circumference and length of second stage of labor are risk factors for levator ani muscle injury, diagnosed by 3-dimensional transperineal ultrasound in primiparous women. Am J Obstet Gynecol. 2009;201(1):91.e91–97.View ArticleGoogle Scholar
- Samuelsson E, Ladfors L, Wennerholm UB, Gareberg B, Nyberg K, Hagberg H. Anal sphincter tears: prospective study of obstetric risk factors. BJOG. 2000;107(7):926–31.View ArticlePubMedGoogle Scholar
- Carroli G, Mignini L. Episiotomy for vaginal birth. The Cochrane database of systematic reviews. 2009;(1):Cd000081.Google Scholar
- Gottvall K, Allebeck P, Ekeus C. Risk factors for anal sphincter tears: the importance of maternal position at birth. BJOG. 2007;114(10):1266–72.View ArticlePubMedGoogle Scholar
- Rygh AB, Skjeldestad FE, Korner H, Eggebo TM. Assessing the association of oxytocin augmentation with obstetric anal sphincter injury in nulliparous women: a population-based, case–control study. BMJ open. 2014;4(7), e004592.View ArticlePubMedPubMed CentralGoogle Scholar
- Samuelsson E, Ladfors L, Lindblom BG, Hagberg H. A prospective observational study on tears during vaginal delivery: occurrences and risk factors. Acta Obstet Gynecol Scand. 2002;81(1):44–9.View ArticlePubMedGoogle Scholar
- Lindgren HE, Radestad IJ, Christensson K, Hildingsson IM. Outcome of planned home births compared to hospital births in Sweden between 1992 and 2004. A population-based register study. Acta Obstet Gynecol Scand. 2008;87(7):751–9.View ArticlePubMedGoogle Scholar
- Hutton EK, Reitsma AH, Kaufman K. Outcomes associated with planned home and planned hospital births in low-risk women attended by midwives in Ontario, Canada, 2003–2006: a retrospective cohort study. Birth (Berkeley, Calif). 2009;36(3):180–9.View ArticleGoogle Scholar
- McPherson KC, Beggs AD, Sultan AH, Thakar R. Can the risk of obstetric anal sphincter injuries (OASIs) be predicted using a risk-scoring system? BMC research notes. 2014;7:471.View ArticlePubMedPubMed CentralGoogle Scholar
- Brocklehurst P, Hardy P, Hollowell J, Linsell L, Macfarlane A, McCourt C, Marlow N, Miller A, Newburn M, Petrou S, et al. Perinatal and maternal outcomes by planned place of birth for healthy women with low risk pregnancies: the Birthplace in England national prospective cohort study. BMJ (Clinical research ed). 2011;343:d7400.View ArticleGoogle Scholar
- Hildingsson IM, Lindgren HE, Haglund B, Radestad IJ. Characteristics of women giving birth at home in Sweden: a national register study. Am J Obstet Gynecol. 2006;195(5):1366–72.View ArticlePubMedGoogle Scholar
- Lindgren H, Kjaergaard H, Olafsdottir OA, Blix E. Praxis and guidelines for planned homebirths in the Nordic countries - an overview. Sex Reprod Healthc. 2014;5(1):3–8.View ArticlePubMedGoogle Scholar
- Lindgren HE, Brink A, Klinberg-Allvin M. Fear causes tears - perineal injuries in home birth settings. A Swedish interview study. BMC Pregnancy Childbirth. 2011;11:6.View ArticlePubMedPubMed CentralGoogle Scholar
- Dahlen HG, Dowling H, Tracy M, Schmied V, Tracy S. Maternal and perinatal outcomes amongst low risk women giving birth in water compared to six birth positions on land. A descriptive cross sectional study in a birth centre over 12 years. Midwifery. 2013;29(7):759–64.View ArticlePubMedGoogle Scholar
- Cortes E, Basra R, Kelleher CJ. Waterbirth and pelvic floor injury: A retrospective study and postal survey using ICIQ modular long form questionnaires. Eur J Obstet Gynecol Reprod Biol. 2011;155(1):27–30.View ArticlePubMedGoogle Scholar
- Smith LA, Price N, Simonite V, Burns EE. Incidence of and risk factors for perineal trauma: a prospective observational study. BMC Pregnancy Childbirth. 2013;13:59.View ArticlePubMedPubMed CentralGoogle Scholar
- Shorten A, Donsante J, Shorten B. Birth position, accoucheur, and perineal outcomes: informing women about choices for vaginal birth. Birth (Berkeley, Calif). 2002;29(1):18–27.View ArticleGoogle Scholar
- Soong B, Barnes M. Maternal position at midwife-attended birth and perineal trauma: is there an association? Birth (Berkeley, Calif). 2005;32(3):164–9.View ArticleGoogle Scholar
- Aikins Murphy P, Feinland JB. Perineal outcomes in a home birth setting. Birth (Berkeley, Calif). 1998;25(4):226–34.View ArticleGoogle Scholar
- Gupta JK, Hofmeyr GJ, Shehmar M. Position in the second stage of labour for women without epidural anaesthesia. The Cochrane Database of Systematic Reviews. 2012;5:Cd002006.Google Scholar
- Naroll F, Naroll R, Howard FH. Position of women in childbirth. A study in data quality control. Am J Obstet Gynecol. 1961;82:943–54.View ArticlePubMedGoogle Scholar
- Kemp E, Kingswood CJ, Kibuka M, Thornton JG. Position in the second stage of labour for women with epidural anaesthesia. The Cochrane Database of Systematic Reviews. 2013;1:Cd008070.Google Scholar
- Blix E, Kumle MH, Ingversen K, Huitfeldt AS, Hegaard HK, Olafsdottir OA, Oian P, Lindgren H. Transfers to hospital in planned home birth in four Nordic countries - a prospective cohort study. Acta Obstet Gynecol Scand. 2016;95(4):420–8.View ArticlePubMedGoogle Scholar
- Homer CS, Thornton C, Scarf VL, Ellwood DA, Oats JJ, Foureur MJ, Sibbritt D, McLachlan HL, Forster DA, Dahlen HG. Birthplace in New South Wales. Australia: an analysis of perinatal outcomes using routinely collected data. BMC Pregnancy Childbirth. 2014;14:206.View ArticlePubMedPubMed CentralGoogle Scholar
- Thiagamoorthy G, Johnson A, Thakar R, Sultan AH. National survey of perineal trauma and its subsequent management in the United Kingdom. Int Urogynecol J. 2014.Google Scholar
- Baghestan E, Irgens LM, Bordahl PE, Rasmussen S. Trends in risk factors for obstetric anal sphincter injuries in Norway. Obstet Gynecol. 2010;116(1):25–34.View ArticlePubMedGoogle Scholar
- Stedenfeldt M, Oian P, Gissler M, Blix E, Pirhonen J. Risk factors for obstetric anal sphincter injury after a successful multicentre interventional programme. BJOG. 2014;121(1):83–91.View ArticlePubMedGoogle Scholar
- Priddis H, Dahlen H, Schmied V. What are the facilitators, inhibitors, and implications of birth positioning? A review of the literature. Women Birth. 2012;25(3):100–6.View ArticlePubMedGoogle Scholar
- De Jonge A, Lagro-Janssen AL. Birthing positions. A qualitative study into the views of women about various birthing positions. J Psychosom Obstet Gynaecol. 2004;25(1):47–55.View ArticlePubMedGoogle Scholar
- Downe S. Physiology and care during the transition and second stage phases of labour. In: Fraser DM, Cooper MA, editors. Myles textbook for midwives. Edinburgh: Churchill Livingstone; 2003.Google Scholar
- How to perform an episiotomy [https://www.rcm.org.uk/news-views-and-analysis/analysis/how-to-perform-an-episiotomy]
- Andrews V, Sultan AH, Thakar R, Jones PW. Occult anal sphincter injuries--myth or reality? BJOG. 2006;113(2):195–200.View ArticlePubMedGoogle Scholar
- Andrews V, Thakar R, Sultan AH. Structured hands-on training in repair of obstetric anal sphincter injuries (OASIS): an audit of clinical practice. Int Urogynecol J Pelvic Floor Dysfunct. 2009;20(2):193–9.View ArticlePubMedGoogle Scholar
- Blix E, Kumle MK, Ingversen K, Huitfeldt AS, Hegaard HK, Ólafsdóttir OÁ, Oian P, Lindgren H. Transfers to hospital in planned home births in four Nordic countries. 2016.Google Scholar
- Aasheim V, Nilsen AB, Lukasse M, Reinar LM. Perineal techniques during the second stage of labour for reducing perineal trauma. The Cochrane database of systematic reviews. 2011(12):Cd006672.Google Scholar