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Obstetrics & Gynecology 2000;96:214-218
© 2000 by The American College of Obstetricians and Gynecologists
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ORIGINAL RESEARCH

Predictors of Episiotomy Use at First Spontaneous Vaginal Delivery

JULIAN N. ROBINSON, MD, ERROL R. NORWITZ, MD, PhD, AMY P. COHEN and ELLICE LIEBERMAN, MD, DrPH

From the Harvard Medical School, Department of Maternal Fetal Medicine, Brigham & Women’s Hospital, Boston, Massachusetts.

Address reprint requests to: Julian N. Robinson, MD Brigham and Women’s Hospital Division of Maternal Fetal Medicine Department of Obstetrics and Gynecology 75 Francis Street Boston, MA 02115 E-mail: jnrobinson{at}bics.bwh.harvard.edu


   Abstract
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Abstract
Materials and Methods
 Results
 Discussion
 References
 
Objective: To identify factors associated with the use of episiotomy at spontaneous vaginal delivery.

Methods: We studied 1576 consecutive term, singleton, spontaneous vaginal deliveries in nulliparas at Brigham & Women’s Hospital between December 1, 1994 and July 31, 1995. The association of demographic variables and obstetric factors with the rate of episiotomy use were examined. Adjusted odds ratios (OR) and confidence intervals (CI) were estimated from multiple logistic regression analysis.

Results: The overall rate of episiotomy was 40.6% (640 of 1576). Midwives performed episiotomies at a lower rate (21.4%) than faculty (33.3%) and private providers (55.6%) (P = .001). After controlling for confounding factors with logistic regression, private practice provider was the strongest predictor of episiotomy use (OR, 4.1; 95% CI, 3.1, 5.4) followed by faculty provider (OR, 1.7; 95% CI, 1.1, 2.5), prolonged second stage of labor (OR, 1.8; 95% CI, 1.2, 2.7), fetal macrosomia (OR, 1.6; 95% CI, 1.1, 2.5), and epidural analgesia (OR 1.4, 95% CI, 1.1, 1.8).

Conclusion: The strongest factor associated with episiotomy at delivery was the category of obstetric provider. Obstetric and demographic factors evaluated did not readily explain this association.

Episiotomy can be used for fetal indications (including nonreassuring fetal testing, preterm delivery, and vaginal breech delivery), maternal indications (maternal exhaustion, prolonged second stage), or to facilitate operative vaginal delivery. Midline episiotomy is preferred over mediolateral episiotomy in North America1–3; however, midline episiotomy is not without cost. In particular, it increases the rate of third and fourth degree perineal laceration.1–3 The long-term effects of anal sphincter damage include maternal incontinence of flatus and feces that can persist for many decades.1–5 Although the use of episiotomy is slowly decreasing in western countries,6–8 the proportion of women who receive episiotomies remains substantial. Despite that, factors associated with the use of episiotomy at spontaneous vaginal delivery have not been studied extensively. This study was done to determine factors associated with episiotomy in spontaneous vaginal delivery at term.


   Materials and Methods
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Abstract
 Materials and Methods
Results
 Discussion
 References
 
We reviewed the medical records of all women who delivered at Brigham and Women’s Hospital between December 1, 1994 and July 31, 1995. The project was approved by the human research committee at the hospital. Practitioners were grouped into three categories according to who performed the delivery. Private practice included all physicians in private practice or part of health maintenance organizations. Faculty included residents (all of whom were supervised by faculty practitioners) and the faculty practice. The midwifery practice included all midwives in independent practice and those of health maintenance organizations. Data related to labor and delivery were extracted from medical records by trained abstractors. The current analysis was limited to nondiabetic nulliparas with singleton pregnancies who delivered vaginally at or after 36 weeks’ gestation. Assisted vaginal deliveries, breech vaginal deliveries, and women who had cardiac conditions or inflammatory bowel diseases were excluded because those conditions could affect the treatment of the second stage of labor. Ninety-eight women were excluded (13 with cardiac conditions, 77 with diabetes, and eight with inflammatory bowel disease). Women with unknown obstetric care providers were also excluded (n = 43). At our institution, episiotomy is not done routinely, and when it is used, it is almost exclusively midline.

The following variables were evaluated for association with episiotomy. Clinical characteristics included type of obstetric care provider (midwife, faculty practice, or private physician), fetal macrosomia (defined as birth weight of at least 4 kg), presence of meconium, use of epidural anesthesia, use of oxytocin (for induction or augmentation of labor), and prolonged second stage of labor (at least 3 hours). Demographic characteristics included maternal age (21 or younger, 22–34, and 34 years or older) and welfare status. We did not evaluate the diagnoses of nonreassuring fetal status because only three women had it (one delivered by midwife, two delivered by private practitioners, two with episiotomies and one without). Although the episiotomy was the primary outcome, significant perineal trauma (third and fourth degree lacerations) were also noted.

The SAS statistical software package (SAS Institute, Cary, NC) was used for statistical analysis. The {chi}2 statistic was used to compare clinical characteristics of women according to episiotomy and obstetric provider. P < .05 was regarded as statistically significant. Logistic regression analysis was done to evaluate the association of different maternal characteristics, obstetric conditions, and obstetric care providers with the use of episiotomy. Obstetric care provider was modeled as two indicator variables for private and faculty physicians, with midwifery practice as the referent group. Maternal age was also modeled as two indicator variables (at most 21 years and at least 35 years) with maternal age of 22–34 years as the referent group.


   Results
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Abstract
 Materials and Methods
 Results
Discussion
 References
 
The overall episiotomy rate was 40.6% (640 of 1576 deliveries). The particular type of episiotomy was clearly documented in 600 of 640 women who had episiotomies. Six of those had mediolateral episiotomies (1%) and 596 had midline episiotomies (99%). The demographics and characteristics of women with and without episiotomies differed significantly in several ways (Table 1Go). Women with episiotomies were more likely than those without to have macrosomic infants, epidural anesthesia, to have labor induced or augmented, or to have a prolonged second stage. Women with episiotomies were less likely to be young or on welfare.


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  		Table 1. Clinical Characteristics
 
When we compared demographics and clinical characteristics of parturients according to type of obstetric care provider (Table 2Go), we found that women cared for by midwives were less likely to receive epidural anesthesia (49.7% versus 75.0% and 77.1% for faculty and private practitioners, respectively) or pitocin (48.3% versus 64.6% and 69.0% for faculty and private practitioners, respectively). Women cared for by private physicians were less likely to be 21 years of age or younger (5.3% versus 26% and 31.6% for faculty and midwives, respectively) or on welfare (3.5% versus 41.2% and 26.6% for faculty and midwives, respectively). There was no difference between providers for macrosomia (8.3% versus 7.3% versus 6.0%) or prolonged second stage (8.5% versus 5.7% versus 10.6%).


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  		Table 2. Clinical Characteristics According to Provider
 
Multiple logistic regression analysis was done to investigate the association between type of obstetric care provider and rate of episiotomy while controlling for confounding factors (Table 3Go). Private practitioners had a fourfold increased use of episiotomy compared with midwives (odds ratio [OR] 4.1; 95% confidence interval [CI] 3.1, 5.4), whereas faculty providers had a rate that was almost double that of midwives (OR 1.7; 95% CI 1.1, 2.5). Other factors associated with episiotomy use were prolonged second stage of labor (OR 1.8; 95% CI 1.2, 2.7), fetal macrosomia (OR 1.6; 95% CI 1.1, 2.5), and epidural analgesia (OR 1.4; 95% CI 1.1, 1.8). Maternal age, welfare status, meconium, and use of oxytocin (for induction or augmentation of labor) were not independently associated with use of episiotomy.


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  		Table 3. Logistic Regression Analysis of Episiotomy Rate
 
Because episiotomy is associated with increased incidence of third and fourth degree perineal lacerations, we also examined that outcome. The rate of third and fourth degree injury was 5.3% (30 of 565) for midwives, 11.5% (22 of 192) for faculty practice, and 10.1% (83 of 819) for private practitioners. Episiotomy was associated with an increased rate of third and fourth degree lacerations at delivery in all three provider groups (Table 4Go). When women with episiotomies and those without them were evaluated separately (using the {chi}2 statistic), there were no significant differences in rates of third or fourth degree perineal lacerations according to category of provider.


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  		Table 4. Percentage of Third and Fourth Degree Laceration by Provider Type and Episiotomy
 

   Discussion
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Abstract
 Materials and Methods
 Results
 Discussion
References
 
Midline episiotomy is associated with increased incidence of third and fourth degree perineal lacerations.1–3 Awareness of independent risk factors might help to reduce its use and decrease unwanted sequelae. Our results showed that, in women who delivered spontaneously at term, the factor most strongly associated with episiotomy was the category of obstetric care provider. The proportion of women who had episiotomies was more than double when cared for by a private practitioner than a midwife (55.6% versus 21.4%). That difference could not be explained by clinical characteristics of parturients or demographic factors. Episiotomies were also more likely to be done if there was fetal macrosomia, prolonged second stage of labor, or if epidural analgesia was used. Maternal age, welfare status, meconium, and use of oxytocin were not independently associated with increased use of episiotomy. No definitive statement could be made regarding nonreassuring fetal testing because few women with it had spontaneous vaginal deliveries. These findings were based on our cohort of 1475 women and our clinical practice and might not be representative of other populations and practices. There is always the possibility that additional confounding variables were not included in our analysis.

The finding that different types of obstetric providers have different propensities for performing episiotomies, which cannot be readily explained by other factors, is consistent with the findings of other investigators.9–12 In a study of 1271 nulliparous women in The Netherlands, Gerrits et al11 showed that registrars (residents) and attending gynecologists were 2.5 and 3.4 times, respectively, more likely than midwives to do episiotomies. In a retrospective study of 8647 deliveries, Heuston13 reported a similar association, with family physicians (OR 0.56, CI 0.48, 0.64) and midwives (OR 0.5, CI 0.38, 0.64) less likely to do episiotomies than obstetricians. However, that study also included multiparous parturients and operative vaginal deliveries, both of which influence use of episiotomy (operative delivery increasing and multiparity decreasing it). When women with and without episiotomies were evaluated separately (Table 4Go), there were no statistically significant differences in rates of third or fourth degree perineal lacerations when compared by category of provider. Thus, although midwives did fewer episiotomies, they did not have a higher rate of severe lacerations among women without episiotomies. Although not conclusive, that finding supports the accepted notion that midline episiotomy leads to sphincter injury. The Cochrane database, in an analysis of six trials that compared restrictive policies of episiotomy with routine use, showed less perineal trauma with restricted use (OR 0.57; 95% CI, 0.46, 0.71).14

We found that prolonged second stage of labor (over 3 hours) was an independent risk factor for episiotomy (OR 1.8, 95% CI 1.2, 2.7). A similar association (OR 1.9, 95% CI 1.5, 2.4) was found if a prolonged second stage was defined as over 1 hour. These data are similar to those of Gerrits et al,11 who reported that a prolonged second stage of labor (over 60 minutes) was a strong determinant of episiotomy. That is in contrast to that of Hueston,13 who reported that a longer second stage was not an independent risk factor for episiotomy in multivariate analysis. Obstetric practitioners might be influenced to use episiotomy by protocols for treatment of the second stage of labor. ACOG recommends that after 3 hours with regional analgesia, or 2 hours without, in nulliparas, the risks and benefits of allowing labor to continue should be assessed and intervention considered.15 Recent studies suggested that length of the second stage can be increased without adverse perinatal outcomes.16,17 If delivery is imminent and fetal condition is reassuring, allowing a judicious extension of the second stage might avoid episiotomy and severe perineal trauma. Prolonged second stage does not differ according to provider and therefore is not a reason for different rates of episiotomies between those groups.

In our cohort, birth weight of greater than 4 kg also was an independent predictor of episiotomy, increasing the chance of it by over 50% (OR 1.6, CI 1.1, 2.5). Hueston,13 using the same definition for fetal macrosomia, documented an almost identical OR (1.47, CI 1.21, 1.71). Gerrits et al.11 found no overall association between birth weight and episiotomy. However, mothers of infants heavier than 4 kg were 1.5 times as likely to receive episiotomies as mothers of infants who weighed 3.5–4 kg, a finding similar to the current study and that of Hueston. Fetal macrosomia rates also do not differ according to provider, therefore this is not a reason for different rates of episiotomy between these groups.

We previously reported an association between epidural use and severe perineal laceration at operative delivery in nulliparas.18 The current analysis shows that epidural analgesia is also an independent risk factor for episiotomy at spontaneous vaginal delivery (OR 1.4, 95% CI 1.1, 1.8). A similar association was found by Heuston13 (OR 1.56, CI 1.21, 2.0). Donnelly et al19 also reported an association between epidural use and anal sphincter damage at first vaginal delivery and suggested that it might be caused by prolonged second stage resulting from epidural analgesia. However, after controlling for length of second stage, we found that the association between epidural analgesia and episiotomy persisted. Whether that was from a lower threshold to perform episiotomy or increased impatience of accoucheurs is not known.

The strongest association with episiotomy was provider category, with lesser associations of birth weight, length of second stage of labor, and use of epidural analgesia. Our findings can be addressed by practitioners modifying any episiotomy practice that is empirical, having patience with epidurals and with reassuring fetal testing, and giving consideration to a longer second stage of labor.


   Footnotes
 
PII S0029-7844(00)00868-1

Received December 17, 1999. Received in revised form February 15, 2000. Accepted March 2, 2000.


   References
Top
Abstract
 Materials and Methods
 Results
 Discussion
 References
 
1. Helwig JT, Thorp JM, Bowes WA. Does midline episiotomy increase the risk of third- and fourth-degree lacerations in operative vaginal deliveries? Obstet Gynecol 1993;82:276–9.[Abstract/Free Full Text]

2. Shiono P, Klebanoff MA, Carey JC. Midline episiotomies: More harm than good? Obstet Gynecol 1990;75:765–70.[Abstract/Free Full Text]

3. Labrecque M, Baillargeon L, Dallaire M, Tremblay A, Pinault JJ, Gingras S. Association between median episiotomy and severe perineal lacerations in primiparous women. CMAJ 1997;156:797–802.[Abstract]

4. Sultan AH, Kamm MA, Hudson CN, Bartram CI. Third degree obstetric anal sphincter tears: Risk factors and outcome of primary repair. BMJ 1994;308:887–91.[Abstract/Free Full Text]

5. Haadam K, Gudmundsson S. Can women with intrapartum rupture of anal sphincter still suffer after-effects two decades later? Acta Obstet Gynecol Scand 1997;76:601–3.[Medline]

6. Reynolds JL, Yudkin PL. Changes in the management of labour: II. Perineal management. CMAJ 1987;136:1045–9.[Abstract]

7. Henriksen TB, Bek KM, Hedegaard M, Secher NJ. Methods and consequences of change in use of episiotomy. BMJ 1994;309:1255–8.[Abstract/Free Full Text]

8. Bansal RK, Tan WM, Ecker JL, Bishop JT, Kilpatrick SJ. Is there a benefit to episiotomy at spontaneous vaginal delivery? A natural experiment. Am J Obstet Gynecol 1996;175:897–901.[Medline]

9. Harvey S, Jarrell J, Brant R, Stainton C, Rach D. A randomized, controlled trial of nurse midwifery care. Birth 1996;23:128–35.[Medline]

10. Heuston WJ, Rudy M. Differences in labor and delivery experience in family physician- and obstetrician-supervised teaching services. Fam Med 1995;27:182–7.[Medline]

11. Gerrits DD, Brand R, Gravenhorst JB. The use of an episiotomy in relation to the professional education of the delivery attendant. Eur J Obstet Gynecol Reprod Biol 1994;56:103–6.[Medline]

12. Klein MC, Kaczorowski J, Robbins JM, Gauthier RJ, Jorgensen SH, Joshi AK. Physicians’ beliefs and behaviour during a randomized controlled trial of episiotomy: Consequences for women in their care. CMAJ 1995;153:769–79.[Abstract]

13. Hueston WJ. Factors associated with the use of episiotomy during vaginal delivery. Obstet Gynecol 1996;87:1001–5.[Abstract]

14. Neilson JP. Evidence-based intrapartum care: Evidence from the Cochrane library. Int J Gynaecol Obstet 1998;63:97–102.

15. American College of Obstetricians and Gynecologists. Operative vaginal delivery. ACOG technical bulletin no. 196. Washington, DC: American College of Obstetricians and Gynecologists, 1994.

16. Menticoglou SM, Manning F, Harman C, Morrison I. Perinatal outcome in relation to second-stage duration. Am J Obstet Gynecol 1995;173:906–12.[Medline]

17. Albers LL, Schiff M, Gorwoda JG. The length of active labor in normal pregnancies. Obstet Gynecol 1996;87:355–9.[Abstract]

18. Robinson JN, Norwitz ER, Cohen A, McElrath TF, Lieberman ES. Epidural analgesia and third- or fourth-degree lacerations in nulliparas. Obstet Gynecol 1999;94:259–62.[Abstract/Free Full Text]

19. Donnelly V, Fynes M, Campbell D, Johnson H, O’Connell PR, O’Herlihy C. Obstetric events leading to anal sphincter damage. Obstet Gynecol 1998;92:955–61.[Abstract]




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