Abstract
Background
Asian American, Native Hawaiian, and Pacific Islander individuals have increased risks for episiotomy and severe perineal laceration during vaginal delivery. The Asian American, Native Hawaiian, and Pacific Islander population in the US is diverse yet few studies disaggregate results within specific ethnicity populations.
Objective
This study investigated the variability in risks for episiotomy and severe perineal laceration among 16 disaggregated Asian American, Native Hawaiian, and Pacific Islander groups, compared to Non-Hispanic White nulliparous individuals, and assessed what factors may explain the variability in risk.
Study design
Birth and fetal death certificate files linked to hospital discharge records were used to identify nulliparous, term, singleton, vertex vaginal deliveries among California births, 2007 to 2020. Poisson regression models were used to examine risks of episiotomy and severe perineal laceration among 16 Asian American, Native Hawaiian, and Pacific Islander ethnicity subgroups compared with Non-Hispanic White individuals. Sequential adjustment was utilized to assess if maternal social, health-related, and delivery-related factors may explain the variability in risk for episiotomy and severe perineal laceration.
Results
Among the 224,964 Asian American, Native Hawaiian, and Pacific Islander individuals in this study cohort, the overall prevalence of episiotomy was 18.5% (N = 41,559) and prevalence of severe perineal laceration was 8.9% (N = 20,013); the prevalence of both outcomes declined during the study period. Within subgroups, prevalence of episiotomy ranged from 9.8% among Other-Pacific Islander individuals to 24.5% among Korean individuals. Prevalence of severe perineal laceration ranged from 3.4% in Guamanian individuals to 15.2% in Indian individuals. In fully adjusted models, risk ratios were greater than 1.0 (with confidence intervals excluding 1.0) for 6 subgroups for episiotomy and 9 subgroups for severe perineal laceration, compared to Non-Hispanic White individuals. After adjustment, Korean individuals were at highest risk of episiotomy (adjusted risk ratio 1.80 [95% CI 1.75, 1.85]), and Indian individuals were at highest risk of severe perineal laceration (adjusted risk ratio 2.14 [95% CI 2.07, 2.21]). Adjustment for social factors (nativity; education; payer) tended to attenuate risk ratios; subsequent adjustment for maternal health and delivery-related factors including maternal age, height, pre-pregnancy body mass index, hypertension, diabetes, gestational weight gain, fetal stress/incomplete fetal head rotation (occiput transverse or posterior), large infant size or shoulder dystocia, and forceps/vacuum did not impact risk ratios substantially.
Conclusion
Prevalence and risks of episiotomy and severe perineal laceration varied widely among Asian American, Native Hawaiian, and Pacific Islander births in California from 2007 to 2020. The variability in risks was more influenced by differences in social rather than maternal health and delivery-related factors. This study adds to the growing understanding of disparities in health outcomes among Asian American, Native Hawaiian, and Pacific Islander subgroups.
Key words: Asian, episiotomy, Hawaiian, Pacific Islander, severe perineal laceration
AJOG Global Reports at a Glance.
Why was this study conducted?
Little is known about how the risks for episiotomy and severe perineal laceration vary among Asian American, Native Hawaiian, and Pacific Islander (AANHPI) ethnicities. We examined the variability in risks for episiotomy and severe perineal laceration among 16 AANHPI ethnicities and assessed factors that may explain the variability.
Key findings
Among AANHPI ethnicities, Korean individuals had the highest prevalence of episiotomy and Indian individuals had the highest prevalence of severe perineal laceration. Risks for episiotomy and severe perineal laceration varied across AANHPI ethnicities. Nativity, education, and payer had the biggest influence on risks; variability in risks was more influenced by social than clinical factors.
What does this add to what is known?
Our study underscores the importance of disaggregating AANHPI ethnicities in health outcomes.
Introduction
Severe perineal laceration (or obstetric anal sphincter injuries—third- or fourth-degree perineal lacerations) and episiotomy affects 6% and 9% of people who give birth vaginally in the United States (US), respectively.1, 2, 3 The standard of care for vaginal deliveries in the United States was previously routine episiotomy with the intent of preventing perineal lacerations; however, evidence has since demonstrated that episiotomy is instead positively associated with severe perineal lacerations which has led to a significant decline in this practice.1,4, 5, 6, 7, 8, 9 Complications from both episiotomy and severe perineal laceration include infection, extreme discomfort during postpartum recovery, postpartum hemorrhage, anal incontinence, and recurrent severe perineal laceration.1,10, 11, 12 Risk factors for episiotomy and severe perineal laceration include nulliparity, advanced maternal age, and higher birth weight, with nulliparity having the largest impact.13
In the US, the greatest prevalences of episiotomy and perineal lacerations occur among the Asian American, Native Hawaiian, and Pacific Islander (AANHPI) population,14, 15, 16, 17, 18 but little is known about how the prevalences of episiotomy and perineal lacerations vary among specific AANHPI ethnicities.19 Although this population is comprised of over 50 unique ethnicities, with substantial diversity in lifestyle, sociodemographic factors, and health disparities,20 research typically aggregates AANHPI ethnicities into a single monolith.16,21 Studies have shown that the prevalence of maternal health outcomes varies among the AANHPI population.19,21,22 The few studies examining variability in the prevalence of episiotomy and severe perineal laceration within AANHPI subgroups have limitations, such as small sample size, investigating only the largest AANHPI subgroups, or combining the effects of social and clinical factors or a sole focus on the latter.18,23, 24, 25, 26 A better understanding of variability could facilitate individualized care for specific AANHPI ethnicities.19
To this end, we sought to investigate (1) variability in risks of episiotomy and severe perineal laceration among 16 AANHPI ethnicities and (2) whether this variability is explained by maternal social, health, and delivery-related factors. We used a population-based dataset of linked vital records and maternal hospital discharge data for California births from 2007 to 2020 for this study. We hypothesized that the risks for episiotomy and severe perineal laceration vary by AANHPI ethnicities.
Materials and methods
Dataset
This study used population-based cohort data from the California Department of Public Health. The dataset contains infant vital records (birth and fetal death certificates) linked to maternal discharge records from the birth hospitalization from 2007 to 2020. Linkage to hospital records was accomplished via probabilistic matching and successful for > 95% of births, as described elsewhere in further detail.27,28
Study population
Starting from a sample of 7,117,629 births, unlinked births (4.7%) were excluded from the study (Supplementary Figure 1). We retained births with maternal AANHPI or Non-Hispanic White (henceforth White) race-ethnicity (N = 2,753,967). Births to individuals who identified as multi-race were excluded from the study (N=147,038). We then restricted the sample to nulliparous, term, singleton, vertex (NTSV) births (N = 1,012,337), and then to vaginal births (N = 708,394). An additional 57,591 (8.1%) births with any missing covariates were excluded, for a complete-case analysis. Our final study population included 650,803 births with 224,964 belonging to individuals who self-reported as AANHPI and 425,839 White individuals.
Study outcomes
Episiotomy involves a surgical incision to the perineum and the posterior vaginal wall during vaginal delivery. Severe perineal laceration (henceforth, severe laceration) is a spontaneous tear to the perineum that is either 3rd degree (injury to the perineum extending to the anal sphincter) or 4th degree (additional damage through to the rectal mucosa). Episiotomy and severe laceration were identified using International Classification of Diseases (ICD), ICD-9 and ICD-10, codes reported in hospital discharge records (Supplementary Table 1).
Study variables
We examined 16 ethnicities across the AANHPI population compared to White individuals, identified using maternal race and ethnicity information from vital records. Available data for AANHPI ethnicities included Chinese, Filipino, Korean, Japanese, Indian, Vietnamese, Cambodian, Hmong, Thai, Laotian, Samoan, Guamanian, Hawaiian, Multi-Ethnic Asian, Other-Asian, and Other-Pacific Islander. Ethnicity was self-reported by individuals, including Other-Asian and Other-Pacific Islander, based on the choices that were provided. The birth and fetal death certificates allow for the selection of up to 3 race-ethnicities. Individuals who reported more than one AANHPI ethnicity (and no non-AANHPI ethnicity) were categorized as Multi-Ethnic Asian. We considered race-ethnicity as a social construct; White individuals are considered as the reference group to reflect their cultural dominance and benefits they have received from social systems in the US.29, 30, 31, 32, 33
Maternal social, health and delivery-related covariates (detailed in Supplementary Table 1 and Supplementary Table 2) were selected a priori based on prior research and our causal diagram (Supplementary Figure 2) showcasing their associations with episiotomy and severe laceration.34, 35, 36, 37, 38, 39, 40 Some covariates were grouped into composites based on likely shared mechanisms or sample size limitations, including: pregestational and pregnancy-related hypertension; pregestational and gestational diabetes; large infant size or shoulder dystocia; indicators of fetal concern (fetal stress, incomplete fetal head rotation (occiput transverse or posterior), or abnormality in fetal heart rate); and forceps or vacuum assisted delivery.34,35,39, 40, 41, 42, 43
Statistical analysis
We used Poisson regression models to evaluate the risk ratios for (1) episiotomy and (2) severe laceration among the AANHPI groups compared to White individuals as the reference group; 95% confidence intervals (CI) were obtained by bootstrapping a 95% sample rate of observations 500 times. We first examined unadjusted risk ratios (Model 0) between AANHPI groups and episiotomy and severe laceration. Then, based on prior research and temporality (Supplementary Figure 2), we grouped covariates into the following categories: maternal social factors (nativity; education; payer), maternal health conditions (maternal age; pre-pregnancy BMI; height, gestational weight gain; hypertension; diabetes), and delivery-related factors (fetal stress/incomplete fetal head rotation (occiput transverse or posterior); large infant size or shoulder dystocia; forceps/vacuum). Our models were sequentially adjusted for maternal social factors (Model 1), then adding maternal health conditions (Model 2), and then adding delivery-related factors (Model 3) to assess the extent to which these factors explained variability in risks for episiotomy and severe laceration (based on changes in risk ratios after adjustment). For severe laceration, we added adjustment for episiotomy (Model 4), which has been reported to be associated with an increased risk of severe perineal laceration.1,4,5,44 Additionally, we performed a sensitivity analysis to evaluate the risk ratios for episiotomy and severe laceration restricted to AANHPI individuals with nonoperative vaginal deliveries (i.e., no use of forceps or vacuum), which prior research has shown to be associated with episiotomy and severe laceration.9,45 Due to small sample size, we did not separately evaluate individuals with operative vaginal deliveries.
The study protocol was approved by the state of California's Committee for the Protection of Human Subjects and the Institutional Review Board of Stanford University. All analyses were performed in SAS 9.4 (Cary, NC).
Results
Population demographics
Among the 16 reported Asian American, Native Hawaiian, and Pacific Islander ethnicities, Chinese (N = 68,114, 30.3%), Indian (N = 37,992, 16.9%), and Filipino (N = 34,910, 15.5%) were the largest groups and Hawaiian (N = 310, 0.1%), Guamanian (N = 410, 0.2%), and Samoan (N = 1,205, 0.5%) were the smallest groups. We observed substantial variability in the distributions of maternal social and health-related factors and delivery-related factors across AANHPI groups (Table 1). For example, Korean, Indian, Japanese, and Chinese subgroups each had over 90% of individuals complete any college compared to Hmong, Samoan, Guamanian, Other-Pacific Islander, Cambodian, and Laotian subgroups who each had less than 60%. Similarly, the majority of Samoan, Other-Pacific Islander, and Hawaiian individuals were over 65 inches tall, whereas most Chinese, Korean, Japanese, Indian, Thai, and Asian-Other individuals were between 63 to < 65 inches tall, and most Hmong individuals were less than 61 inches tall.
Table 1.
Maternal social, health, and delivery-related factors among AANHPI and NH White individuals, California births, 2007 to 2020 (N = 650,803)
| Group N |
Chinese 68,114 |
Filipino 34,910 |
Korean 16,617 |
Japanese 7,912 |
Indian 37,992 |
Vietnamese 21,198 |
Cambodian 4,264 |
Hmong 5,414 |
Thai 2,313 |
Laotian 1,862 |
Samoan 1,205 |
Hawaiian 310 |
Guamanian 410 |
Asian-Other 12,553 |
PI-Other 2,585 |
Multi-Ethnic Asian 7,305 |
NH White 425,839 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Maternal Social Factors | |||||||||||||||||
|
Nativity (%) Foreign-born |
84.2 | 65.1 | 79.9 | 71.5 | 91.0 | 79.3 | 52.0 | 30.0 | 84.8 | 40.9 | 27.6 | 0.7 | 44.6 | 56.2 | 48.7 | 37.4 | 13.2 |
|
Education (%) Any College |
93.0 | 86.7 | 95.6 | 92.3 | 93.5 | 74.5 | 51.1 | 55.5 | 85.3 | 52.6 | 38.0 | 60.3 | 51.2 | 84.1 | 54.2 | 85.3 | 77.7 |
| High School/GED |
6.0 | 11.3 | 4.1 | 7.3 | 5.4 | 20.8 | 35.0 | 32.0 | 12.5 | 33.9 | 50.6 | 27.7 | 38.5 | 12.8 | 38.0 | 11.3 | 18.2 |
| < High School | 1.1 | 2.0 | 0.3 | 0.5 | 1.1 | 4.7 | 14.0 | 12.5 | 2.2 | 13.5 | 11.4 | 11.9 | 10.2 | 3.1 | 7.9 | 3.4 | 4.2 |
|
Payer (%) Public Insurance or Uninsured |
34.3 | 25.4 | 22.1 | 13.5 | 15.4 | 32.5 | 53.1 | 63.4 | 35.9 | 52.0 | 60.4 | 40.7 | 36.3 | 27.9 | 46.4 | 22.7 | 23.7 |
| Maternal Health-Related Factors | |||||||||||||||||
|
Age (years) (%) <20 |
0.3 | 7.4 | 0.3 | 0.5 | 0.3 | 1.8 | 12.3 | 20.1 | 2.2 | 16.5 | 19.8 | 17.7 | 19.3 | 3.5 | 12.6 | 5.3 | 6.6 |
| 20–34 | 81.7 | 81.4 | 76.5 | 63.8 | 92.2 | 82.9 | 80.0 | 77.9 | 75.1 | 75.4 | 77.3 | 73.6 | 74.4 | 81.2 | 80.7 | 77.4 | 79.9 |
| ≥ 35 | 18.1 | 14.4 | 23.2 | 35.8 | 7.4 | 15.3 | 7.7 | 2.1 | 22.7 | 8.2 | 2.9 | 8.7 | 6.3 | 15.3 | 6.7 | 17.3 | 13.6 |
|
Height (inches) (%) <61 |
6.6 | 20.6 | 4.5 | 12.8 | 7.2 | 22.2 | 19.2 | 45.1 | 12.2 | 23.9 | 6.7 b | 7.1 | 16.1 | 11.7 | 8.2 | 13.9 | 2.8 |
| 61 - <63 | 23.3 | 34.4 | 21.3 | 32.0 | 23.2 | 37.0 | 35.2 | 35.5 | 28.3 | 36.0 | 19.4 | 34.4 | 28.2 | 17.0 | 30.2 | 12.0 | |
| 63 - <65 | 36.7 | 28.6 | 37.5 | 32.6 | 36.6 | 28.4 | 29.1 | 15.2 | 34.2 | 26.2 | 20.5 | 32.3 | 28.3 | 32.7 | 24.8 | 32.4 | 24.7 |
| ≥65 | 33.4 | 16.4 | 36.7 | 22.7 | 33.0 | 12.4 | 16.4 | 4.2 | 25.3 | 14.0 | 72.8 | 41.3 | 21.2 | 27.4 | 49.9 | 23.6 | 60.6 |
|
Pre-pregnancy BMI (kg/m2) (%) <18.5 |
15.9 | 6.7 | 14.1 | 13.9 | 6.9 | 17.1 | 12.4 | 4.3 | 14.2 | 8.3 | 1.2 | 51.6c | 52.7c | 9.2 | 5.1 | 8.5 | 5.0 |
| 18.5 - <25 | 73.4 | 65.0 | 75.1 | 74.4 | 66.3 | 72.2 | 64.7 | 54.5 | 69.7 | 62.9 | 22.6 | 69.8 | 40.3 | 67.8 | 62.3 | ||
| 25 - <30 | 9.0 | 20.1 | 8.8 | 9.2 | 21.5 | 8.6 | 16.1 | 26.2 | 12.1 | 19.5 | 31.5 | 24.8 | 23.4 | 15.8 | 27.2 | 16.7 | 20.7 |
| ≥30 | 1.7 | 8.3 | 2.0 | 2.6 | 5.3 | 2.1 | 6.8 | 15.0 | 4.0 | 9.3 | 44.7 | 23.6 | 23.9 | 5.2 | 27.4 | 7.1 | 12.0 |
| Hypertension (%)a | 3.9 | 11.0 | 4.4 | 5.1 | 6.3 | 4.1 | 5.4 | 5.8 | 5.5 | 7.7 | 12.5 | 11.6 | 13.7 | 6.6 | 11.8 | 7.7 | 9.4 |
| Diabetes (%)a | 12.1 | 13.5 | 7.9 | 8.0 | 15.8 | 14.1 | 8.5 | 9.9 | 12.7 | 8.7 | 6.7 | 9.4 | 10.7 | 12.1 | 11.2 | 11.1 | 5.5 |
| Gestational Weight Gain (kg) (Mean, SD) | 13.9 (4.9) | 14.7(5.5) | 14.0(4.9) | 12.4(4.4) | 13.7(5.1) | 14.1(4.9) | 14.2(5.5) | 12.9(5.7) | 14.5(5.2) | 14.5(5.7) | 19.3(9.9) | 16.2(7.0) | 16.4(7.1) | 14.2(5.2) | 16.3(8.1) | 14.5(5.4) | 15.6(6.2) |
| Delivery-Related Factorsa | |||||||||||||||||
| Fetal Stress/Fetal Head Malrotation(%)a | 21.6 | 25.8 | 22.1 | 20.9 | 27.7 | 22.7 | 20.8 | 24.8 | 22.7 | 21.5 | 19.8 | 19.4 | 21.7 | 26.0 | 27.2 | 26.1 | 23.0 |
| Large Infant Sizea or Shoulder Dystocia (%) | 3.3 | 3.7 | 3.9 | 3.0 | 3.5 | 2.7 | 2.6 | 2.8 | 3.8 | 3.2 | 13.7 | 9.4 | 6.3 | 4.1 | 7.9 | 3.6 | 8.1 |
| Forceps/Vacuum (%) | 12.6 | 12.7 | 16.7 | 13.8 | 15.1 | 17.2 | 13.3 | 10.8 | 13.8 | 12.8 | 6.7 | 10.7 | 8.3 | 10.8 | 10.0 | 9.7 | 9.7 |
Abbreviations: AANHPI Asian American Native Hawaiian Pacific Islander, PI Pacific Islander, NH White Non-Hispanic White, BMI body mass index, SD standard deviation.
See Supplementary Table 2 for detailed variable definitions
Cells reflect sum of height (inches) <61 and 61 - < 63 due to small sample size
Cells reflect sum of a BMI <18.5 and 18.5 - <25 due to small sample size.
See Supplementary Table 1 for list of ICD codes examined.
Chidyausiku. Episiotomy and severe perineal laceration among Asian American, Native Hawaiian, and Pacific Islander nulliparous individuals in California. Am J Obstet Gynecol 2025.
Prevalence and risk ratios for episiotomy
In the AANHPI population, the overall prevalence of episiotomy was 18.9%; it declined substantially during the study period, from 24.5% in 2007 to 7.6% in 2020 (Supplementary Figure 3). Prevalence varied from 9.8% among Other-Pacific Islander individuals to 24.5% among Korean individuals and was 12.6% among White individuals (Table 2). Among the 16 subgroups, all but two (Hawaiian and Other-Pacific Islander) had crude risks for episiotomy higher than the White subgroup (Table 2). In fully adjusted models, six subgroups had risks greater than 1.0 with CI's excluding 1.0; Korean (1.80, 95% CI 1.75, 1.85), Vietnamese (1.69, 95% CI 1.65, 1.74), and Chinese (1.56, 95% CI 1.53, 1.59) individuals had the highest risk ratios for episiotomy compared to White individuals, and PI-Other individuals had lower risk (0.69, 95% CI 0.60, 0.77). When considering sequential adjustment, the largest changes in risk ratios for most groups occurred after adjustment for social factors, and 7 subgroups switched from higher risk (risk ratio > 1.0) to lower risk (risk ratio < 1.0) relative to White individuals after this adjustment. Adjustment for health and delivery-related factors resulted in much more modest change in risk for most groups.
Table 2.
Risk of episiotomy among AANHPI individuals compared to NH White individuals among vaginal NTSV births, California, 2007 to 2020, with sequential adjustment for social, health-related and delivery-related factors
| Risk Ratio (95% CI) |
|||||
|---|---|---|---|---|---|
| Number of cases (Prevalence per 100 births) |
Model 0a (Unadjusted) |
Model 1b (+ Social Factors) |
Model 2c (+ Health-Related Factors) |
Model 3d (+ Delivery-Related Factors) |
|
| Korean | 4,076 (24.53) | 1.95 (1.90–2.00) | 1.75 (1.69–1.80) | 1.71 (1.66–1.76) | 1.80 (1.75–1.85) |
| Vietnamese | 5,171 (24.39) | 1.94 (1.89–1.99) | 1.63 (1.59–1.68) | 1.61 (1.57–1.66) | 1.69 (1.65–1.74) |
| Chinese | 16,241 (23.84) | 1.90 (1.86–1.92) | 1.59 (1.56–1.62) | 1.55 (1.52–1.58) | 1.56 (1.53–1.59) |
| Cambodian | 776 (18.2) | 1.45 (1.35–1.55) | 1.16 (1.08–1.24) | 1.15 (1.08–1.23) | 1.17 (1.09–1.25) |
| Japanese | 1,293 (16.34) | 1.30 (1.22–1.37) | 1.23 (1.16–1.29) | 1.23 (1.16–1.30) | 1.24 (1.17–1.31) |
| Laotian | 286 (15.36) | 1.22 (1.08–1.35) | 1.01 (0.89–1.12) | 1.02 (0.90–1.12) | 1.03 (0.91–1.14) |
| Multi-Asian Ethnicity | 1,104 (15.11) | 1.20 (1.12–1.27) | 1.16 (1.08–1.22) | 1.16 (1.09–1.23) | 1.16 (1.08–1.22) |
| Hmong | 810 (14.96) | 1.19 (1.11–1.27) | 0.96 (0.89–1.02) | 0.98 (0.91–1.05) | 0.98 (0.91–1.05) |
| Thai | 311 (13.45) | 1.07 (0.94–1.18) | 0.88 (0.78–0.99) | 0.89 (0.78–0.99) | 0.90 (0.80–1.00) |
| Samoan | 159 (13.20) | 1.05 (0.91–1.20) | 0.85 (0.74–0.97) | 0.92 (0.80–1.06) | 0.89 (0.78–1.03) |
| Filipino | 4,535 (12.99) | 1.03 (1.01–1.06) | 0.93 (0.91–0.96) | 0.96 (0.93–0.99) | 0.97 (0.95–1.00) |
| Asian—Other | 1,623 (12.93) | 1.03 (0.98–1.08) | 0.93 (0.89–0.97) | 0.93 (0.89–0.97) | 0.93 (0.89–0.98) |
| Indian | 4,832 (12.72) | 1.01 (0.98–1.04) | 0.91 (0.89–0.94) | 0.91 (0.89–0.94) | 0.96 (0.93–0.99) |
| Guamanian | 52 (12.68) | 1.01 (0.76–1.27) | 0.88 (0.66–1.10) | 0.93 (0.70–1.16) | 0.90 (0.68–1.14) |
| Hawaiian | 37 (11.94) | 0.95 (0.66–1.22) | 0.89 (0.62–1.13) | 0.92 (0.64–1.17) | 0.93 (0.65–1.17) |
| PI—Other | 253 (9.79) | 0.78 (0.69–0.87) | 0.65 (0.57–0.72) | 0.68 (0.60–0.76) | 0.69 (0.60–0.77) |
| NH White | 53,578 (12.58) | 1.00 | 1.00 | 1.00 | 1.00 |
Abbreviations: AANHPI Asian American Native Hawaiian Pacific Islander, PI Pacific Islander, NH White Non-Hispanic White, NTSV Nulliparous Term Singleton Vertex, CI Confidence Interval, BMI body mass index.
Model 0: AANHPI subpopulation is the only independent variable
Model 1 = Model 0 + education + payment + nativity
Model 2 = Model 1 + maternal age + pre-pregnancy BMI + height + gestational weight gain + hypertension + diabetes
Model 3 = Model 2 + fetal stress/fetal head malrotation + large infant size or shoulder dystocia + forceps/vacuum.
A total of 650,803 births, 95,137 of which had episiotomy, were included in each model.
Chidyausiku. Episiotomy and severe perineal laceration among Asian American, Native Hawaiian, and Pacific Islander nulliparous individuals in California. Am J Obstet Gynecol 2025.
Prevalence and risk ratios for severe perineal laceration
In the AANHPI population, the overall prevalence was 8.9%. Prevalence declined from 10.9% in 2007 to 7.2% in 2020 (Supplementary Figure 3). Prevalence ranged from 3.4% among Guamanian individuals to 15.2% among Indian individuals, compared to 5.4% among White individuals. Among the 16 AANHPI subgroups, all but three (Guamanian, Hawaiian, and Samoan) had risks higher than the White subgroup (Table 3). In fully adjusted models, nine subgroups had risks greater than 1.0 with CI's excluding 1.0. Risks for Indian (2.14, 95% CI 2.07, 2.21), Hmong (1.51, 95% CI 1.36, 1.67), and Filipino (1.38, 95% CI 1.33, 1.44) individuals were the highest; only the risk ratios for Hawaiian and Guamanian individuals remained less than 1.0, but sample sizes were smallest for these two groups and confidence intervals included 1.0. Regarding sequential adjustment, the greatest change in risk ratios tended to occur with adjustment for social factors and more modest change after adjustment for health and delivery-related factors. Further adjusting for episiotomy (Model 4) did not substantially change risk ratios.
Table 3.
Risk of severe perineal laceration among AANHPI individuals compared to NH White individuals among vaginal NTSV births, California, 2007 to 2020, with sequential adjustment for social, health-related and delivery-related factors
| Risk Ratio (95% CI) |
||||||
|---|---|---|---|---|---|---|
| Number of cases (Prevalence per 100 births) | Model 0a (Unadjusted) |
Model 1b (+ Social Factors) |
Model 2c (+ Health-Related Factors) |
Model 3d (+ Delivery-Related Factors) |
Model 4e (+ Episiotomy) |
|
| Indian | 5,781 (15.22) | 2.84 (2.76–2.92) | 2.25 (2.18–2.32) | 2.20 (2.13–2.28) | 2.14 (2.07–2.21) | 2.14 (2.07–2.21) |
| Vietnamese | 1,912 (9.02) | 1.68 (1.60–1.76) | 1.47 (1.40–1.55) | 1.32 (1.26–1.40) | 1.27 (1.20–1.34) | 1.27 (1.20–1.34) |
| Filipino | 3,147 (9.01) | 1.68 (1.62–1.75) | 1.46 (1.40–1.52) | 1.37 (1.32–1.43) | 1.38 (1.33–1.44) | 1.38 (1.33–1.44) |
| Thai | 205 (8.86) | 1.65 (1.43–1.87) | 1.41 (1.22–1.60) | 1.32 (1.14–1.50) | 1.33 (1.16–1.51) | 1.33 (1.16–1.51) |
| Asian—Other | 1,035 (8.25) | 1.54 (1.44–1.63) | 1.38 (1.28–1.46) | 1.30 (1.22–1.38) | 1.35 (1.26–1.43) | 1.35 (1.26–1.43) |
| Cambodian | 323 (7.58) | 1.41 (1.27–1.56) | 1.44 (1.29–1.60) | 1.34 (1.20–1.48) | 1.37 (1.23–1.51) | 1.37 (1.23–1.51) |
| Hmong | 408 (7.54) | 1.40 (1.27–1.55) | 1.54 (1.40–1.70) | 1.45 (1.31–1.60) | 1.51 (1.36–1.67) | 1.51 (1.36–1.67) |
| Korean | 1,213 (7.30) | 1.36 (1.28–1.44) | 1.12 (1.05–1.19) | 1.07 (1.01–1.14) | 1.02 (0.96–1.08) | 1.02 (0.96–1.08) |
| Japanese | 569 (7.19) | 1.34 (1.24–1.45) | 1.11 (1.02–1.20) | 1.04 (0.95–1.12) | 1.04 (0.95–1.12) | 1.04 (0.95–1.12) |
| Laotian | 126 (6.77) | 1.26 (1.07–1.49) | 1.31 (1.12–1.54) | 1.23 (1.04–1.45) | 1.24 (1.06–1.46) | 1.24 (1.06–1.46) |
| Chinese | 4,583 (6.73) | 1.25 (1.22–1.30) | 1.05 (1.02–1.09) | 1.00 (0.97–1.04) | 1.03 (0.99–1.07) | 1.03 (0.99–1.06) |
| Multi-Asian Ethnicity | 471 (6.45) | 1.20 (1.10–1.30) | 1.11 (1.01–1.20) | 1.04 (0.95–1.13) | 1.10 (1.00–1.19) | 1.10 (1.00–1.19) |
| PI—Other | 158 (6.11) | 1.14 (0.96–1.32) | 1.15 (0.96–1.33) | 1.18 (0.99–1.37) | 1.20 (1.01–1.39) | 1.20 (1.01–1.39) |
| Samoan | 56 (4.65) | 0.87 (0.65–1.11) | 0.99 (0.75–1.27) | 1.10 (0.84–1.41) | 1.13 (0.87–1.43) | 1.13 (0.87–1.43) |
| Hawaiian | 12 (3.87) | 0.72 (0.31–1.17) | 0.80 (0.35–1.29) | 0.82 (0.36–1.31) | 0.78 (0.34–1.25) | 0.78 (0.34–1.25) |
| Guamanian | 14 (3.41) | 0.64 (0.30–0.97) | 0.64 (0.31–0.98) | 0.64 (0.31–0.99) | 0.69 (0.32–1.04) | 0.69 (0.32–1.04) |
| NH White | 22,851 (5.37) | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 |
Abbreviations: AANHPI Asian American Native Hawaiian Pacific Islander, PI Pacific Islander, NH White Non-Hispanic White, NTSV Nulliparous Term Singleton Vertex, CI Confidence Interval, BMI body mass index.
Model 0: AANHPI subpopulation is the only independent variable
Model 1 = Model 0 + education + payment + nativity
Model 2 = Model 1 + maternal age + pre-pregnancy BMI + height + gestational weight gain + hypertension + diabetes
Model 3 = Model 2 + fetal stress/fetal head malrotation + large infant size or shoulder dystocia + forceps/vacuum
Model 4 = Model 3 + episiotomy
A total of 650,803 births, of which 42,864 had a severe perineal laceration, were included in each model.
Chidyausiku. Episiotomy and severe perineal laceration among Asian American, Native Hawaiian, and Pacific Islander nulliparous individuals in California. Am J Obstet Gynecol 2025.
Sensitivity analysis
We examined risks for episiotomy and severe laceration among AANHPI ethnicities with nonoperative vaginal deliveries (i.e., we included 578,873 of 650,803 births in the main analysis). The pattern of results was similar to the main findings, such as the largest changes in risks for episiotomy and severe laceration for most groups occurred after adjusting for social factors (Supplemental Table 3; Supplemental Table 4). Risk ratios were not reported for Hawaiian and Guamanian individuals due to small sample size.
Comment
Principal findings
We found that many AANHPI ethnicities were at greater risk for episiotomy and severe laceration compared to White individuals, and among the 16 AANHPI ethnicities, maternal social factors (nativity; education; payer) seemed more explanatory of the variability in risks for episiotomy and severe laceration than maternal health-related and delivery-related factors (based on a greater change in risk after adding these variables to the models). Additionally, substantial variability in risks exists across AANHPI ethnicities for episiotomy and severe laceration. Relative to White individuals, we observed 9 subgroups with decreased risk of episiotomy (e.g., 30% decrease in risk among Other-Pacific Islander individuals) and 2 subgroups with decreased risk of severe laceration (e.g., 30% decrease in risk among Guamanian individuals). In contrast, 7 subgroups had elevated risk of episiotomy (e.g., almost a two-fold increase in risk among Korean individuals) and 14 subgroups with elevated risk of severe laceration (e.g., over a two-fold increase in risk among Indian individuals).
Result
Studies investigating the risks of episiotomy and severe laceration have consistently found that Asian individuals (as a single group) are at greater risk compared to other racial-ethnic groups in the US.14, 15, 16 We are unaware of studies investigating the risk of episiotomy among disaggregated AANHPI ethnicities. There are a few studies investigating the risk of severe laceration among Chinese, Filipino, and Indian individuals. A study by Hopkins et al.23 utilizing data from the University of California, San Francisco hospital system included four AANHPI ethnicities (N = 4,261) (Chinese; Filipino; Japanese; Other-Asian) to assess variability in risk of perineal (including but not limited to severe cases), vaginal, or cervical laceration from 1976 through 2001. The study cohort included nulliparous, term, vertex vaginal births but did not explicitly restrict to singleton gestation. Filipino individuals had the highest odds of severe laceration (1.92, 95% CI 1.64, 2.25) and Japanese individuals had the lowest odds (1.01, 95% CI 0.69, 1.47). Additionally, a study by Handa et al.26 included four AANHPI ethnicities (N = 215,791) (Indian; Filipino; Other-Asian; Other-Pacific Islander) and utilized similar linked data on California vaginal births as our study but looked at earlier birth years (1992 through 1997). The study population was term, singleton, vertex vaginal births, but it did not restrict to nulliparous individuals. Findings were similar to our study regarding patterns of prevalence and risk of severe laceration among the four studied AANHPI ethnicities. Our inclusion of more recent years and more AANHPI ethnicities expands on the findings in Handa et al. and suggests that the variability in risk among AANHPI subgroups have persisted over time. Additionally, both studies examined similar covariates as our study but did not include BMI nor perform a sequential adjustment of the covariates.
Our study also highlights that for most AANHPI ethnicities, being at higher risk for episiotomy did not necessarily correlate with higher risk for severe laceration, and vice versa. For example, relative to White individuals, Indian individuals had decreased risk for episiotomy yet had over a two-fold elevated risk for severe laceration. Similarly, Korean individuals had an almost two-fold elevated risk for episiotomy despite a risk for severe laceration close to null. In contrast, ethnicities like Cambodian, Japanese, and Multi-Asian had similar adjusted risk ratios for episiotomy and severe laceration. This suggests that the risk factors impacting episiotomy and severe laceration may differ within AANHPI ethnicities.
Our findings show that adjustment for maternal social factors had the greatest impact on risks for episiotomy and severe laceration compared with maternal health-related and delivery-related factors across AANHPI subgroups. We observed a minimal attenuation of risk ratios after adjusting for maternal health and delivery-related factors. Prior work has found delivery-related factors, such as operative vaginal delivery, to be the predominant risk factors for severe laceration; however, these results did not include the effect of social factors on severe laceration nor assess disaggregated racial-ethnic groups.14,15,34,35 Our investigation of maternal social factors in sequentially adjusted results suggest that maternal social factors could play a larger role within the AANHPI population. Social factors in our study (nativity; education; payer) had a larger effect on risks which may reflect disadvantages to racial-ethnic minority populations in the US health care system through avenues such as healthcare quality, healthcare coverage, and health facility accessibility.46
Clinical implications
Variability in risks for episiotomy and severe laceration remained after adjustment. Other factors beyond those in our study may explain these differences: e.g., differences in clinician care practices such as performing routine episiotomy or perineal support during delivery, and years in clinical practice.47,48 Raising provider awareness of the variability in risks for episiotomy and severe laceration among AANHPI ethnicities and implementing clinical interventions, like perineal massage or application of a warm compress to the perineum during the second stage of labor, may prevent an episiotomy and severe laceration from occurring and reduce the disparities we observe in the rates of episiotomy and severe laceration.49, 50, 51 Findings from various studies have shown conflicting results regarding episiotomy and its effect on severe laceration.51, 52, 53, 54 However, it remains that adjusting for episiotomy did not explain higher risks for severe laceration among AANHPI ethnicities when compared to White individuals.
Research implications
Individual AANHPI populations show significant variations in risks for episiotomy and severe laceration. Disaggregation of AANHPI ethnicities provides a better understanding of disparities experienced among these populations and promotion of health interventions that are more equitable and effective. A systematic review investigating AANHPI racial and ethnic disparities in maternal health observed less than half of studies disaggregated AANHPI ethnicities.21 Our findings support that risks among Native Hawaiian and Pacific Islander ethnicities differ substantially from Asian American ethnicities; hence if sample size does not permit complete disaggregation, studies should consider at the very least distinguishing between these two populations. It is established that systemic biases in the US health care system result in better health outcomes in the White population; our findings of 6 AANHPI ethnicities being at a significantly higher risk for episiotomy and 9 for severe laceration compared to White individuals add further evidence.46 In our study population, a majority of individuals in most AANHPI subgroups were foreign-born. Research has shown that cultural factors, such as language and being an immigrant, influence health among Asian Americans and can be major barriers to healthcare access in AANHPI populations.55, 56, 57 Additionally, social factors had the largest effect on risks for episiotomy and severe laceration. Therefore, we encourage future research to further investigate how social and cultural factors of AANHPI ethnicities impact AANHPI health.
Strengths and limitations
Strengths of our study include the large and diverse population of California, which accounts for 1 out of 8 births in the US annually, and the high linkage rate (95%) representing the majority of NTSV births among the AANHPI and White population in California. This allowed for the disaggregation of smaller subgroups, such as Hmong, Cambodian, Laotian, Thai, Samoan, and Guamanian that often are added into a larger composite group or excluded altogether.16,21,58 Our study had several limitations. First, our study used self-reported race-ethnicity as the primary proxy for the experiences of AANHPI ethnicities, but we acknowledge there may also be heterogeneity of experience and risk related to other factors such as principal language and acculturation. Second, severe laceration was defined by ICD-9 and -10 codes based on provider notation, but we recognize that variability in classifying severity of laceration may exist among providers.3 Furthermore, we did not have data on provider type or transfer of care between providers in our study, although prior research has reported that these factors are associated with our study outcomes.9 Third, our cohort excluded 2.2% (92,099) of births to individuals who identified as multi-race, which may have included individuals with any AANHPI heritage. However, our study did include multi-ethnic AANHPI individuals as a subgroup. Given the lack of literature on single AANHPI ethnicities and expected heterogeneity within this multi-race group, we focused primarily on individuals with a single AANHPI ethnicity but suggest that future studies include individuals of any AANHPI ethnicity. Fourth, we limited our cohort to nulliparous births due to the increased risks of episiotomy and severe laceration seen in this population. Although this decreased our cohort size, it is important to focus on the nulliparous population as they have much higher rates of episiotomy and severe lacerations.
Conclusions
We found that the risks for episiotomy and severe laceration were variable across AANHPI ethnicities, and for most groups, risks were higher than that observed for White individuals. Adjustment for social, health-related, and delivery-related factors explained some, but not all, excess risk, with social factors (nativity; education; payer) having the biggest effect on the risks for episiotomy and severe laceration. This study underscores the importance of disaggregating AANHPI ethnicities in the context of common, impactful health outcomes related to giving birth.
CRediT authorship contribution statement
Tracy Chidyausiku: Writing – review & editing, Writing – original draft, Visualization, Software, Project administration, Methodology, Investigation, Formal analysis, Data curation, Conceptualization. Shalmali Bane: Writing – review & editing, Software, Methodology, Conceptualization. Meryl M. Sperling: Writing – review & editing, Methodology. Elliott K. Main: Writing – review & editing, Methodology, Funding acquisition, Conceptualization. Suzan L. Carmichael: Writing – review & editing, Supervision, Project administration, Methodology, Conceptualization.
Acknowledgments
The authors would like to thank Peiyi Kan for statistical support. This work was supported by the Eunice Kennedy Shriver National Institute of Child Health & Human Development (R01 HD103662).
Footnotes
Patient consent: The study protocol was approved by the state of California's Committee for the Protection of Human Subjects and the Institutional Review Board of Stanford University.
Conflict of interest: The authors report no conflict of interest.
This paper was supported by the Eunice Kennedy Shriver National Institute of Child Health & Human Development (R01 HD103662). The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH. The funders had no role in study design. Analyses, interpretations, and conclusions reached regarding birth and fetal death data are attributed to the authors and not to the California Department of Public Health.
Supplementary material associated with this article can be found in the online version at doi:10.1016/j.xagr.2025.100450.
Appendix. Supplementary materials
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