A univariate analysis of the association of episiotomy with clinical characteristics was performed. Decreased episiotomy rates were significantly associated with non-white race of the mother (63.8% for whites versus 39.4% for blacks, 47.2% for Asians, and 40.6% for Hispanics, P < .001), if the mother was on Medicaid insurance (28.4% versus 47.4%, P < .001), SVDs (43.3% versus 82.8%, P < .001), in patients older than 21 years (49.1% for patients 22–34 and 49.9% for patients older than 34 versus 55.4% for age less than 21, P < .001), and if the infant was small for gestational age (41.6% versus 50.5%, P < .001). Large-for-gestational-age deliveries were associated with a nonsignificant decrease in episiotomy rate (50.5% versus 45.2%, P = .09). Women having a third-or fourth-degree perineal laceration were significantly more likely to have received an episiotomy (85.4% versus 46.5%, P < .001).
The first multivariable model of episiotomy is presented in Table 1. This model includes year of childbirth plus all the factors from the univariate analysis except Medicaid status, which was not available until 1990. This table shows a statistically significant reduction in risk of episiotomy with increasing year of birth and maternal age greater than 21. Black race showed the most dramatic risk reduction (odds ratio [OR] 0.29, 95% confidence interval [CI] 0.28, 0.31), with less significant reductions for Asians (OR 0.71, 95% CI 0.60, 0.84) and Hispanics (OR 0.54, 95% CI 0.43, 0.68). Significant positive association with episiotomy was found in women delivered with forceps and with those who experienced third- or fourth-degree perineal laceration.
A multivariable logistic regression model including insurance information is constructed on the subset of data occurring from 1990 to 2000, 18,138 vaginal births. This model shows that controlling for insurance status, the factors still significantly associated with a decreased risk of episiotomy include increasing year of childbirth (OR 0.82, 95% CI 0.81, 0.83), black race (OR 0.31, 95% CI 0.28, 0.34), Asian race (OR 0.78, 95% CI 0.65, 0.93), Hispanic race (OR 0.61, 95% CI 0.47, 0.80), maternal age 22–34 years (OR 0.49, 95% CI 0.45, 0.54), age greater than 35 years (OR 0.45, 95% CI 0.40, 0.51), and SVD (OR 0.34, 95% CI 0.30, 0.39). Receiving Medicaid insurance was also associated with a decreased episiotomy risk (OR 0.59, 95% CI 0.54, 0.64). Increased association with episiotomy was seen in forceps deliveries (OR 3.53, 95% CI 2.90, 4.28), and with third- or fourth-degree lacerations (OR 3.92, 95% CI 3.44, 4.47). Non-significant changes in episiotomy risk were seen in the women who delivered large-for-gestational-age (OR 1.13, 95% CI 0.77, 1.66) or small-for-gestational-age infants (OR 1.05, 95% CI 0.77, 1.43).
To try to control for parity, we selected the subset of births known to be from multiparous women. A multivariable logistic regression model with GEE is presented for this subgroup in Table 2. The model is based on 4075 multiparous births from 1990 to 2000 to enable the inclusion of insurance status in this model. Although there is some loss of power in the smaller covariate categories, the general magnitude and trend of the ORs remain the same as in the previous models.
Although the use of selective episiotomy is advocated in the literature, there is little evidence on whether the practice of performing episiotomies has actually decreased or not over the last 20 years. We found a statistically significant reduction in the overall episiotomy rate between 1983 and 2000 from 69.6% to 19.4%. The OR of 0.87 per year of childbirth in Table 1 reflects a statistically significant reduction in episiotomy rates per year from 1983 through 2000. This change in practice pattern may be largely due to the impact of a growing body of literature against routine episiotomy, including that derived from randomized controlled trials. Additionally, improved patient education and participation in decision making and changes in use of forceps and vacuum assistance probably play a role in reducing the overall number of episiotomies. No specific policy or educational initiative regarding episiotomy was implemented during the study period.
We also found that white women consistently underwent episiotomy more frequently than black women. It was initially hypothesized that the difference between races in episiotomy rates may have been due to differences in parity, prenatal care, or in the number of operative vaginal deliveries. Episiotomies remained significantly greater in white patients, however, despite multivariable logistic regression analysis controlling for these possible confounding factors. Socioeconomic and racial differences have been reported for obstetric practices and procedure rates, including cesarean delivery, epidural use, and episiotomy, with higher socioeconomic status increasing the risk for intervention. Hueston reported white race as a predictor for episiotomy (OR 2.02, CI 1.66, 2.46). He hypothesized that the increased episiotomy rate could represent a marker for patient expectations or perceived threat of a malpractice suit.11 Howard et al's study similarly found an increased episiotomy rate (34.8% versus 22.3%, P = .003) in white patients compared with black patients.12 It also showed that black primiparas were less likely to deliver with second-degree or greater vaginal lacerations and more likely to deliver with their perineums intact, supporting anecdotal reports of lower vaginal laceration rates in black women.12 Physician perception of differing risks of severe spontaneous lacerations between racial groups may also factor into white women undergoing episiotomy more often in a misguided attempt to prevent this. It may also simply be a marker of the arbitrary and non-scientific nature employed by the physician in determining which patients need an episiotomy.
Our study is retrospective, and it is limited by a database unable to supply information on nulliparity, epidural usage, specific infant weight, and insurance information before 1990. Secondary analyses of the multiparous subgroup were used to attempt to control for parity as best possible in assessing our results. Even in the multiparous subgroup, the association of episiotomy with race remained consistent. Physician turnover during the 18 years studied may have affected episiotomy rates; however, given that 55.7% of the deliveries were performed by 20 physicians, it is unlikely that practices of a few would have significantly affected the results.
Our findings of a decreasing rate of episiotomy between 1983 and 2000 agrees with national trends.8 Although our overall episiotomy rates appear lower than national rates, the proportion of black women in our population is larger than national demographics. Further investigation is needed to examine trends in episiotomy rates among other academic institutions and community and rural hospitals in different geographic areas.
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© 2002 The American College of Obstetricians and Gynecologists
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