The U.S. rates for both total and nulliparous, term, singleton, vertex cesarean delivery rose by 50% in the decade between 1997 and 2007 and have plateaued recently.1 Although cesarean birth can be life-saving for both mother and neonate, the rise in cesarean delivery rates was not associated with any demonstrable improvement in maternal or neonatal morbidity or mortality.2 Nevertheless, it remains unknown whether programs to actively support vaginal birth and reduce primary cesarean delivery rates will affect neonatal and maternal outcomes. Some observers have worried that implementing new labor management guidelines may even increase the rates of neonatal morbidity.3
The California Maternal Quality Care Collaborative (CMQCC) has undertaken a wide variety of large scale (More than 100 hospitals) quality improvement (QI) collaboratives that have addressed early elective deliveries, maternal mortality, and severe morbidity related to obstetric hemorrhage and hypertension.4 Key partners have included the California Department of Public Health, the California districts of professional organizations, the California Hospital Association, and a variety of public and patient organizations. After publication of American College of Obstetricians and Gynecologists and Society for Maternal-Fetal Medicine (ACOG–SMFM) guidelines for safely reducing primary cesarean deliveries,2 release of the CMQCC Toolkit to Support Vaginal Birth and Reduce Primary Cesareans,5 publication of the Council for Patient Safety in Women's Health Care Patient Safety Bundle: Safe Reduction of Primary Cesarean Birth6 and commentary,7 and testing of QI tools in hospital pilot projects in 2014–2015, CMQCC embarked on a statewide QI project to improve labor support and reduce cesarean births among nulliparous mothers. This report examines whether the project was associated with adverse maternal or neonatal outcomes.
California hospitals whose nulliparous, term, singleton, vertex cesarean delivery rates were above the Healthy People 2020 goal of 23.9% in 2015 were invited to participate in the Supporting Vaginal Birth collaborative led by CMQCC. Fifty-six hospitals initiated two cohorts of collaborative activities in mid-2016. Participating hospitals were organized into small teams of six to eight hospitals each led by a physician and a nurse mentor who provided clinical expertise and QI coaching.8 The mentors were from other hospitals and had experience in prior CMQCC quality collaboratives. The collaborative focused on implementation of ACOG–SMFM guidelines for labor management2,6,7 and on increasing nursing labor support.5 A modified Institute for Healthcare Improvement Breakthrough Series collaborative model9 was used with monthly team check-in phone calls and sharing of implementation ideas and materials. Hospitals received training materials, Grand Rounds for physicians and nurses, educational webinars, and on-site assistance from their mentors. The California Maternal Data Center provided analysis of improvement opportunities and monthly reports comparing hospital progress benchmarked against peers both within the collaborative and statewide. Hospital teams also were able to network with other teams across the state with a comprehensive curated and indexed listserv. More details on the collaborative activities will be reported in future publications.
Since the launching of the collaborative in 2016, we observed a significant decline in nulliparous, term, singleton, vertex cesarean delivery rate in participating hospitals, which underscored the need for an analysis of project safety. Neonatal and maternal safety or “balancing” measures were monitored monthly to identify unintended consequences for maternal and neonatal health. In this report, we conducted a cross-sectional study (before and after for the same facilities) to evaluate whether a reduction in nulliparous, term, singleton, vertex cesarean delivery would be associated with neonatal or maternal outcomes.
Clinical data to calculate the neonatal and maternal balancing measures were collected as part of routine care for all births from 2015 throughout the study period and reported monthly to the California Maternal Data Center. Maternal measures included rates of obstetrician-defined chorioamnionitis, transfusions of red blood cells, third- or fourth-degree lacerations among vaginal deliveries, and operative vaginal delivery. The primary neonatal measure was the National Quality Forum–endorsed composite outcome metric: severe unexpected newborn complications.10 The severe unexpected newborn complications metric was designed to be a balancing measure for obstetric QI projects and focuses on singleton term neonates without preexisting conditions. Neonates with congenital anomalies, genetic conditions, hydrops, exposure to maternal drug use, and birth weights less than the 10th percentile are excluded. Criteria for the severe unexpected newborn complications composite include hypoxic ischemic encephalopathy, seizures, ventilation, neonatal sepsis, major birth injuries, and hospital transfer to a higher level of care. Length of stay modifiers are added to guard against undercoding and overcoding of complications (for example, the International Classification of Diseases (ICD) code for neonatal sepsis requires a minimum of a 4-day length of stay to be included, thus excluding neonates erroneously coded to rule out sepsis). A second neonatal measure collected was the rate of 5-minute Apgar scores less than 5.
The measures used in this study had been routinely reported by California hospitals to the CMQCC data center for 5 years. Data quality education programs were run annually by CMQCC and several of the metrics have ongoing data quality surveillance performed monthly by the Data Center. Outlier data was followed up by requests for investigation and correction but were uncommon. Several of the measures (nulliparous, term, singleton, vertex cesarean delivery, unexpected newborn complications, third- or fourth-degree lacerations) were also used for reporting to outside agencies providing extra scrutiny.
The California Maternal Data Center obtained birth certificate clinical data from the California Department of Public Health, Center for Health Statistics, for all California births 45 days after the end of each month. Maternal and neonatal discharge files containing diagnosis, procedure and disposition codes were also sent directly from the hospitals on a monthly basis. On a semi-annual basis (but delayed by 6–9 months), the Office of Statewide Health Planning and Development provided a file including maternal and neonatal discharge files for all births in the state used to confirm the data provided directly from the hospitals. These data were linked and maintained in the CMQCC California Maternal Data Center. A probabilistic linkage algorithm modified from a previously published methodology11 was used to monthly link birth certificate data with mother's discharge data with linkage rates routinely exceeding 98%. Institutional review board approval was obtained from Stanford University as the study host, and the California Committee for the Protection of Human Subjects for the use of the state data sets.
There were 357,323 births from the 56 hospitals in the study period (2015–2017). Using Joint Commission PC-02 criteria,12 we identified 126,480 nulliparous, term, singleton, vertex births in these facilities. Term birth was defined as those with obstetric estimated gestational age between 37 and 44 weeks as recorded on the birth certificate. Plurality and presentation were obtained using maternal discharge diagnosis codes. International Classification of Diseases 9th or 10th Revision, Clinical Modification (ICD-9-CM or ICD-10-CM) diagnosis and procedure codes were also used to identify women who have experienced chorioamnionitis, blood transfusions, third- or fourth-degree lacerations after vaginal delivery, and operative vaginal delivery (Appendix 1, available online at http://links.lww.com/AOG/B298). Neonates with severe unexpected newborn complications were identified using the National Quality Forum–endorsed algorithm, which uses data from both the birth certificate and the neonatal discharge file.10
Maternal and newborn sociodemographic and clinical characteristics were also acquired. Maternal race–ethnicity, maternal prepregnancy body mass index (BMI), maternal education levels, prenatal care, and neonatal birth weight were obtained from the birth certificate. Maternal age at delivery was calculated using the mother's birth date on the maternal discharge record and the newborn's birth date on the birth certificate. Insurance status was obtained from the maternal discharge record; if it was missing, information from the birth certificate was used. Maternal comorbidities including chronic hypertension, diabetes, and gestational diabetes were identified using ICD-9-CM or ICD-10-CM diagnosis and procedure codes (Appendix 1, available online at http://links.lww.com/AOG/B298).
Teaching hospital status, hospital geographic region, and hospital ownership were obtained from the Office of Statewide Health Planning and Development. Level of neonatal care was derived as a self-reported variable based on the 2012 definition set forth by the American Academy of Pediatrics.13 Hospitals in rural areas were identified using definitions provided by the Health Resources & Services Administration.14
We calculated half-yearly rates for nulliparous, term, singleton, vertex cesarean delivery and other maternal and neonatal outcome measures from 2015 to 2017. We conducted a before-after analysis to estimate the risk of each outcome measure comparing women in the first full year of the QI collaborative (2017) to those in the baseline period (2015). We used unconditional logistic regression model to estimate odds ratios (ORs) and 95% CIs. Considering the hierarchical structure of the data, with births nested within hospitals, we used mixed-effect models with hospital at delivery as random intercept. The following risk factors for cesarean delivery and other outcome measures were considered in multivariable models: maternal age, maternal race-ethnicity, maternal prepregnancy BMI, maternal education levels, insurance status, prenatal care, neonatal birth weight, and maternal comorbidities including chronic hypertension, type I and type II diabetes, and gestational diabetes (Table 1). For race–ethnicity, because some hospitals had limited numbers of black nulliparous patients with term, singleton, vertex pregnancies, we combined black women, Asian women, and women with other race into one category in the risk-adjustment analysis.
All analyses included nulliparous, term, singleton, vertex births at all 56 hospitals except for the analysis for the severe unexpected newborn complications composite, which included nulliparous, term, singleton, vertex births at only 51 hospitals. Early in the study, five hospitals contracted their neonatal intensive care unit ownership to a children's hospital, with the consequence that all neonates admitted to the neonatal intensive care unit were identified as transferred to higher level of care, automatically categorizing them as having severe unexpected newborn complications. Furthermore, data on neonatal complications in the records at the delivering facility were severely limited. Subsequently, complication diagnoses and length of stay data were collected from these five hospitals in the most recent year (2017) using a combination of chart reviews and supplemental files. Rates of severe unexpected newborn complications in these five hospitals showed a decreasing trend similar to that observed in other collaborative hospitals. However, we did not combine their severe unexpected newborn complications rates with those of the other facilities in this analysis because their data were collected using a substantively different method.
We then examined maternal and neonatal outcomes among hospital groups when stratified by absolute rate reduction on nulliparous, term, singleton, vertex cesarean delivery. We calculated nulliparous, term, singleton, vertex cesarean delivery rate reduction for each hospital and categorized them into terciles. Hospitals in the first tercile (n=19) had the greatest decline in nulliparous, term, singleton, vertex cesarean delivery rate with a mean absolute reduction of 10.9 percentage points. The mean absolute reduction rate for hospitals in the second (n=18) and the third tercile (n=19) was 4.4 and 0.3 percentage points, respectively. Half-yearly rates for each outcome measure and before-after analysis were carried out within each tercile group. An additional analysis examined outcomes among hospitals that had the lowest ending nulliparous, term, singleton, vertex cesarean delivery rates—those below 20% (n=10). To address the issue of multiple testing, we adopted the false discovery rate approach to identify potential false-positive findings,15 which has been recommended as an alternative to more conservative Bonferroni-type adjustments.16 Hypothesis tests were 2-sided with a significance level of 0.05. All statistical analyses were performed using SAS 9.4.
In 2015, nulliparous, term, singleton, vertex cesarean delivery rate ranged from 11.3% to 76.9% in 248 California hospitals with maternity services. Approximately 60% (n=147) of the California hospitals had rates higher than the Healthy People 2020 goal of 23.9%. Fifty-six hospitals, all among those with initial rates above 23.9% participated in CMQCC's Supporting Vaginal Birth collaborative. The collaborative hospitals represented a mix of hospital types: teaching and nonteaching hospitals; rural and urban hospitals; university, community, and integrated health system; and high, medium and small delivery volume (Table 2). The mix was quite similar to the state as a whole, with the exceptions of fewer hospitals with less than 1,000 annual births and fewer hospitals under university or integrated health system ownership reflecting the population of hospitals with higher nulliparous, term, singleton, vertex cesarean delivery rates. The study population included an annual average of 119,000 deliveries, of which 35% were nulliparous, term, singleton, vertex births. Approximately 36% of births were among white women and 38% among Hispanic women. Medicaid or other government-sponsored programs covered around one third of births. Compared with 2015, a slightly higher percentage of nulliparous, term, singleton, vertex births in 2017 were to women with higher risk for a cesarean delivery, for example, older age at delivery, obese, and with maternal comorbidities (Table 1).
The overall nulliparous, term, singleton, vertex cesarean delivery rates declined by 4.5 percentage points (a relative decline of 15.5%), from 29.1% in the first two quarters in 2015 to 24.6% in the last two quarters in 2017 (Fig. 1). The largest decline happened in the third and fourth quarters of 2016, when the collaborative initiated. Compared with women in 2015 (baseline year), those in 2017 (first full year of collaborative) were significantly less likely to give birth by cesarean (OR 0.80, 95% CI 0.78–0.83). The OR was further reduced to 0.76 (95% CI 0.73–0.78) after the adjustment for maternal and newborn risk factors. Rates of severe unexpected newborn complications, transfusion, chorioamnionitis, 5-minute Apgar score less than 5, third- or fourth-degree perineal lacerations, and operative vaginal birth did not change throughout the collaborative time period (Fig. 1 and Table 3, overall QI collaborative). Of the operative vaginal deliveries, 92.5% were via vacuum extractor. Both the before and after rates appear elevated compared with national rates of operative delivery for all births, but rates reported in this study are restricted to term singleton nulliparous women who would be expected to have higher rates.
Individual hospital nulliparous, term, singleton, vertex cesarean delivery rates declined over a broad range, from −17.1 to +4.7 percentage points. This allowed us to perform a sensitivity analysis to examine whether the size of the reduction in cesarean delivery rate might be related to changes in neonatal and maternal complications. Hospitals were divided into terciles based on degree of reduction. Hospitals with the greatest declines in nulliparous, term, singleton, vertex cesarean delivery rate showed no significant changes in their low Apgar scores, chorioamnionitis, transfusion, laceration, or operative vaginal birth rates (Table 3, hospitals with greatest absolute decline in nulliparous, term, singleton, vertex cesarean delivery rate). Rates of severe unexpected newborn complications actually declined from 3.2% in 2015 to 2.2% in 2017 in this group, with an adjusted OR of 0.71 (95% CI 0.55–0.92) comparing women in 2017 to those in 2015.
Neonatal and maternal complications among hospitals in the middle and the least tercile of absolute declines in nulliparous, term, singleton, vertex cesarean delivery rates also did not increase over the course of the intervention period (Table 3, hospitals with middle absolute decline in nulliparous, term, singleton, vertex cesarean delivery rate and hospitals with least absolute decline in nulliparous, term, singleton, vertex cesarean delivery rate) with the single exception of chorioamnionitis in the middle absolute decline tercile. In that group, the 18 hospitals reported a slight increase in obstetrician-diagnosed chorioamnionitis, with an adjusted OR of 1.10 (95% CI 1.01–1.19; false discovery rate–adjusted P-value did not reach statistical significance level of .05) (Table 3, hospitals with middle absolute decline in nulliparous, term, singleton, vertex cesarean delivery rate). This increase was not noted in any other group, including the tercile with the greatest decline (adjusted OR 0.90, 95% CI 0.78–1.04) (Table 3, hospitals with greatest absolute decline in nulliparous, term, singleton, vertex cesarean delivery rate), nor in the collaborative as a whole (adjusted OR 1.04, 95% CI 0.98–1.10) (Table 3, overall QI collaborative).
Twenty-four of the 56 participating hospitals lowered their nulliparous, term, singleton, vertex cesarean delivery rates to below the Healthy People 2020 target of 23.9% in 2017. Ten of them lowered the rates even further, to below 20% (range 15.0–19.9%). Similar to the analysis based on the absolute amount of decline shown above, we did not observe an increase in adverse maternal or neonatal outcomes even among those with these lower final rates (Table 3, hospitals with 2017 nulliparous, term, singleton, vertex cesarean delivery rate between 15.0% and 19.9%). Rates of severe unexpected newborn complications also declined from 2.5% in 2015 to 2.2% in 2017 in this group, but not significantly with an adjusted OR of 0.84 (95% CI 0.58–1.20).
In a large-scale quality collaborative associated with nulliparous, term, singleton, vertex cesarean delivery rates, we noted no worsening in a variety of neonatal and maternal safety indicators. The size of this study is noteworthy. Fifty-six hospitals participated with a total annual delivery volume of 119,000 women. This is a higher delivery volume than in all but nine U.S. states.17 All hospitals in the collaborative had a starting nulliparous, term, singleton, vertex cesarean delivery rate higher than the Healthy People 2020 national target of 23.9%.18 Importantly, the majority of collaborative hospitals were community hospitals (87%), representing the predominant care model in the United States.19
Some obstetricians harbor apprehensions about reducing their current high cesarean delivery rates, often citing a 1999 New England Journal of Medicine Sounding Board article, “The Risks of Lowering the Cesarean Delivery Rate.”20 The total cesarean delivery rate at that time was 21%, and the authors were concerned that a new national goal for a total cesarean delivery rate of 15%, “may have a detrimental effect on maternal and infant health.” Not often cited, however, is their conclusion that total cesarean delivery rates above 21% should be amenable to reduction. More recently, Cohen worried about neonatal effects of the new labor guidelines, particularly for extended duration of second stage labor.3,21 Subsequently, a series of studies have been published examining the outcomes of broad-based cesarean delivery reduction QI projects.22–26 None of these studies show any decline in maternal and neonatal safety measures, but they largely represent single academic centers, which limit their power for less common neonatal outcomes and their generalizability to the more common community hospital setting. The clustered randomized trial in Quebec included an annual average of 52,500 deliveries27 and was able to show a modest decline in their primary cesarean delivery rate (22.5%–21.8%) and modest reductions in both major and minor neonatal morbidities. In contrast, Rosenbloom et al28 note that their academic center's labor management practices changed over time in concert with the ACOG–SMFM labor recommendations (without a formal QI collaborative). However, their primary cesarean delivery rate did not change, and their maternal and neonatal morbidities actually increased. The majority of studies that specifically focused on longer second stage management (longer than 3 hours or longer than 4 hours) have found small incremental increases in neonatal morbidity as duration lengthened.29–31
The CMQCC Supporting Vaginal Birth collaborative interventions emphasized reducing latent phase cesarean deliveries, implementation of ACOG–SMFM guidelines for diagnosis and management of active phase disorders, and enhanced nursing support (increased walking and upright positioning, use of peanut balls, and interpersonal coaching). Providers did not increase their operative vaginal delivery rates. Our findings provide evidence that a reduction in first birth cesarean delivery rates need not be associated with more difficult vaginal births or higher rates of major perineal lacerations.
Key strengths of this report are the large number of facilities engaged (particularly community hospitals) and the large decline in the nulliparous, term, singleton, vertex cesarean delivery rate, allowing a greater examination of potential risks for lowering the cesarean delivery rate. The large number of nulliparous, term, singleton, vertex deliveries provided the ability to confidently examine maternal and neonatal complications that are infrequent. The range of improvement among the 56 hospitals created the opportunity to perform a sensitivity analysis comparing hospitals with very high levels of cesarean delivery rate reduction (−17.1 to −7.1 percentage points) with those with limited change (−2.4 to +4.7 percentage points). The lack of increase in neonatal complications among all subgroups was particularly reassuring. The rate of severe unexpected newborn complications (the major composite index for neonatal outcomes) actually improved in hospitals with the greatest reduction in nulliparous, term, singleton, vertex cesarean delivery rate. This is in concordance with several of the single hospital studies noted above.22–26
Limitations of the study reflect the nature of a large quality collaborative involving 56 hospitals. Data for outcome measures were collected as part of normal patient care and not by formal study staff. Birth certificate, discharge diagnosis and procedure files and supplemental data were submitted to the collaborative monthly. Feedback regarding completeness was provided immediately back to hospital teams with the opportunity to update data submissions. Another limitation is the before and after design which requires analysis for alternative explanations for the observed results.32 Changes in ICD coding did occur during 2015, but the rates of third- or fourth-degree lacerations, transfusions, and severe unexpected newborn complications were not affected. Changes in the composition of patient population between time periods were minor and adjusted for. In addition, the ability to compare the same hospitals in a before and after design provided controls for unit practices and micro-culture not otherwise accounted for by general hospital characteristics. Another limitation is that even with 56 hospitals, we may not have enough statistical power to detect a small difference for the very low frequency safety measures, such as a low Apgar score.
In summary, the variation in nulliparous, term, singleton, vertex cesarean delivery rates among California hospitals was astounding, ranging from 11% to 77% and provided substantial incentive for QI efforts. Our findings that large reductions in cesarean delivery rates need not lead to worse neonatal or maternal outcomes is important for other hospitals and health systems embarking on this journey.
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