Optimal cesarean birth rate

INTRODUCTION — Cesarean birth is performed when this method of birth is believed to be more advantageous for the mother and/or fetus than vaginal birth. The cesarean birth rate is reported in various ways. For example:

●The overall cesarean birth rate is the number of cesarean births per 100 live births.

●The primary cesarean birth rate is the number of cesarean births per 100 live births among patients with no prior cesarean birth.

●The US Centers for Disease Control and Prevention (CDC) also report a low-risk cesarean birth rate, which is the number of cesarean births per 100 live births among nulliparous patients, at ≥37+0 weeks of gestation, delivering a singleton in cephalic presentation (also called the nulliparous term singleton vertex [NTSV] cesarean birth rate). However, this rate is problematic because of the term "low risk," which is not defined in the conventional manner as a pregnancy without medical or obstetrical complications.

The optimal cesarean birth rate, which we define as the rate that minimizes maternal and neonatal morbidity and mortality, is not known and likely varies by patient population (including at the institutional and individual-practice level). The rise in the overall cesarean birth rate in the United States over the past several decades (5.5 percent of births in 1970, 16.5 percent in 1980, 21 percent in 1996, 32.1 percent in 2021 [1,2]) has raised the question of whether the rate is too high since the rising rate has not been associated with favorable trends in severe maternal morbidity or severe neonatal morbidity.

This topic will discuss what an optimal cesarean birth rate might be and safe reduction of the cesarean birth rate in practices where the rate is higher than optimal. Other issues related to primary cesarean birth are reviewed separately:

●(See "Cesarean birth: Preoperative planning and patient preparation".)

●(See "Cesarean birth: Surgical technique".)

●(See "Cesarean birth: Postoperative care, complications, and long-term sequelae".)

●(See "Cesarean birth on patient request".)

APPROPRIATE APPROACH TO INTERPRETATION OF OBSTETRIC OUTCOMES BY MODE OF BIRTH — When analyzing the various outcomes for cesarean versus vaginal birth, researchers should compare the intended birth route rather than the actual route (ie, planned cesarean versus planned trial of labor) since approximately 20 to 30 percent of planned labors end in intrapartum cesarean birth, which is associated with higher morbidity than cesarean birth before labor. When the correct comparison group is used, the higher risk for some adverse outcomes with cesarean birth reported in some retrospective observational studies is no longer observed.

In a meta-analysis of 16 randomized trials comparing outcomes of planned cesarean with planned trial of labor, neonatal and maternal mortality were similar in both groups [3-17]. For the newborn, planned cesarean births were less likely to result in birth trauma, hypotonia, and tube feeds; for the mother, planned cesarean births were less likely to result in chorioamnionitis, urinary incontinence at ≤3 months and at one to two years postpartum, and perineal pain at two years. The trials included patients with: preterm and breech births (four trials), breech presentation (three trials), twins (two trials), prior cesarean birth (two trials), eclampsia (two trials), HIV infection (one trial), prior anal sphincter tear (one trial), and umbilical arterial blood samples (one trial). Limitations of these data are that most participants had risk factors for cesarean birth (ie, not always nulliparous term singleton vertex [NTSV]) and the longer term outcomes were mostly reported by the large trials on delivery of the term breech [18] and twins [3]. Importantly, outcomes of future pregnancies often were not ascertained and could be worse with prior cesarean versus a trial of labor. Therefore, these findings should not be interpreted as supportive of a high rate of planned cesarean birth in the general obstetric population.

WHY DOES A NONOPTIMAL CESAREAN BIRTH RATE MATTER?

Downstream effects of a high cesarean birth rate — A higher than optimal cesarean birth rate has some significant downstream effects:

●Short-term maternal risks of cesarean birth include infection, hemorrhage, injury to pelvic/abdominal organs, and venous thrombosis/embolism. Cesarean birth is associated with more postpartum pain and longer hospital stay and longer recovery time compared with vaginal birth. Short-term neonatal risks of planned cesarean birth are neonatal respiratory morbidities (eg, transient tachypnea of the newborn, respiratory distress syndrome), persistent pulmonary hypertension of the newborn, and neonatal intensive care unit (NICU) admission [19-22]. (See "Cesarean birth: Postoperative care, complications, and long-term sequelae", section on 'Complications'.)

●A long-term risk of cesarean birth is the increased risk for abnormal placentation in subsequent pregnancies with associated risks of morbidity and mortality. Literature from the 1970s and 1980s estimated an incidence of placenta accreta spectrum (PAS) was 1 in 2510 to 4017 births, but a study from 2016 representing the National Inpatient Sample estimated the PAS rate to be 1 in 272 [23]. While there are several factors that have likely contributed to this rapid rise in PAS, one of the most significant is the rise in the cesarean birth rate. (See "Placenta accreta spectrum: Clinical features, diagnosis, and potential consequences", section on 'Risk factors'.)

●Other long-term complications of cesarean birth include the potential for development of clinically significant abdominal/pelvic adhesions, which can lead to bowel obstruction or subfertility. (See "Cesarean birth: Postoperative care, complications, and long-term sequelae", section on 'Long-term risks'.)

●In addition, patients who undergo cesarean birth have a uterine scar. If the patient becomes pregnant again, there is a small but potentially serious risk of rupture of the scar or cesarean scar pregnancy (see "Uterine rupture: After previous cesarean birth" and "Cesarean scar pregnancy"). The type of scar affects decision-making regarding the mode of birth in subsequent pregnancies. (See "Choosing the route of delivery after cesarean birth".)

Downstream effects of a low cesarean birth rate — A lower than optimal cesarean birth rate also has some significant downstream effects. Overall, the following data suggest that a cesarean birth rate below 15 to 20 percent may be too low, as it appears to jeopardize the health of the mother and/or the newborn. However, the optimal lowest safe cesarean birth rate may vary among low-, middle-, and high-income countries.

●In a large retrospective review comparing cesarean birth rates versus neonatal mortality in three Dublin hospitals between 1979 and 2000, rates below 15 to 20 percent were associated with higher neonatal mortality (figure 1) [24].

●In 1985, the World Health Organization (WHO) recommended national target cesarean birth rates no higher than 10 to 15 percent (ie, 10 to 15 cesareans per 100 live births) [25-27]. However, in a subsequent large cross-sectional study estimating annual cesarean births rates from data collected between 2005 and 2012 for all 194 WHO member states (22.9 million births), national cesarean birth rates ≥19 percent (19 cesareans per 100 live births) were associated with less maternal and neonatal mortality than lower rates [26].

WHAT DO PATIENTS WANT? — Consideration of an individual's values and priorities in choosing the mode of birth is a component of person-centered decision-making in obstetrics. When surveyed, most nulliparous patients with term singleton cephalic fetuses and uncomplicated pregnancies state that their preferred mode of giving birth is vaginally. Only a small minority such patients, about 1 to 5 percent in the United States and about 3 percent globally, prefer a cesarean birth (so called cesarean delivery on maternal request [CDMR]) [28]. (See "Cesarean birth on patient request".)

For example, a study in the United States that explored patient preferences regarding mode of birth found 90.8 percent desired a vaginal birth, but the preferences varied by the need for labor and delivery interventions, with certain interventions leading to a preference for an uncomplicated planned cesarean [29]. When midwives in Sweden were surveyed, fewer than 1 percent preferred a CDMR for a normal pregnancy at term [30]. By comparison, in a survey of Flemish obstetricians, 16 percent desired a CDMR for themselves or their partner for an uncomplicated term cephalic singleton pregnancy [31]. In addition, a survey of Turkish obstetricians observed that many desired CDMR and those under age 44 were more likely to opt for a CDMR for themselves or their partners than their older colleagues (90 versus 50 percent) [32]. Similar surveys have been performed worldwide with a wide range of findings.

On the other hand, a small minority of obstetricians is so against CDMR that they would not perform it even if a patient desires it after counseling. The American College of Obstetricians and Gynecologists (ACOG) states that it is the provider's right to decline to perform a CDMR, but a referral to another provider should be facilitated [33].

HOW SHOULD CESAREAN BIRTH RATES BE MEASURED AND WHAT IS OPTIMAL? — Health systems vary widely with respect to the populations they care for, so it is important to take this and other variations into account when comparing cesarean birth rates. One example is the system proposed by Robson [34], which involves taking any given obstetric population and dividing it into 10 groups of similar risk, and then comparing the cesarean rate over time within a specific group. This avoids calculating a single overall cesarean rate that has little meaning because the patients within the overall population are so different and have different a priori risks for cesarean. Instead, the system allows within-group comparisons and between-group comparisons (eg, the identification of specific groups where the cesarean rate is rising as well as those groups where it is not), thus helping clinicians identify targeted strategies to reduce unnecessary rise.

The 10 Robson categories are [34]:

●Nulliparous, singleton cephalic, ≥37 weeks, in spontaneous labor

●Nulliparous, singleton cephalic, ≥37 weeks, induction or prelabor cesarean

●Multiparous, no previous cesarean, singleton cephalic, ≥37 weeks, in spontaneous labor

●Multiparous, no previous cesarean, singleton cephalic, ≥37 weeks, induction or prelabor cesarean

●Previous cesarean birth, singleton cephalic, ≥37 weeks

●All nulliparas with breech presentation

●All multiparas (including those with previous cesarean) with breech presentation

●All multiple gestations (including those with previous cesarean)

●All abnormal lies (including those with previous cesarean)

●All singleton cephalic, ≤36 weeks (including those with previous cesarean)

Within this patient grouping system, it is important to recognize that the most important outcome is achieving the lowest maternal and perinatal morbidity and mortality possible, coupled with the highest maternal satisfaction. Thus, the optimal cesarean birth rate for each group should be the one that achieves these goals. However, there are inherent potential pitfalls to all scoring systems, and some consider the best use of this one to be comparing trends within groups across time or institutions, whereas comparing trends across groups may lead to erroneous conclusions.

It is also important to recognize that much of the variation in cesarean birth rates among institutions and patient groups is not due to differences in medical or obstetric factors (eg, parity, rate of multiple gestation), but to differences in social environment and social interactions, including disparities related to race and ethnicity. As an example, in the United States, the primary cesarean birth rate in 2021 by race and ethnicity was: non-Hispanic Black patients 26.2 percent, non-Hispanic Asian patients 23.9 percent, non-Hispanic Native Hawaiian or Pacific Islander patients 22.6 percent, non-Hispanic White patients 21.9 percent, and Hispanic patients 20.8 percent [35].

A new index for obstetrics safety and quality of care that integrates cesarean birth rates with maternal and neonatal outcomes has been developed [36]. The goal was to establish a valid outcomes quality measure that encompassed preexisting high-risk maternal factors and associated maternal and neonatal morbidities and was acceptable to patients, healthcare providers, payers, and governmental agencies. Use of this novel single metric may help to identify ways of improving clinician practice standards and balance cesarean birth rates with optimal maternal and neonatal outcomes. We believe that cesarean birth rates should be a quality metric only in the context of accounting for all these factors. Indeed, not accounting for patient characteristics and risk factors, and most importantly, for maternal and perinatal outcomes, is not useful and potentially harmful.

SELECTED STRATEGIES FOR SAFE REDUCTION OF THE CESAREAN BIRTH RATE — The cesarean birth rate, if higher than optimal among some groups of patients, is a multifactorial challenge. It is unlikely that a single approach will be effective for optimizing the rate and/or reducing the rate in some populations. Instead, incorporating emerging evidence suggesting clinical management strategies that reduce cesarean birth rates and/or maternal/neonatal morbidity should be adopted. The following trial provided level I evidence for a practice change that can be implemented for all patients. It is an example of high-quality emerging science that works towards positively impacting the cesarean birth rate and maternal and newborn morbidity.

●Induction at 39^th weeks of gestation – In 2018, a multicenter trial randomly assigned low-risk nulliparous patients to labor induction at 39+0 to 39+4 weeks or to expectant management until 40+5 weeks [37]. Induction at 39 weeks resulted in a reduced risk of cesarean (18.6 versus 22.2 percent; relative risk [RR] 0.84, 95% CI 0.76-0.93) as well as improvements in some other outcomes (reduced rates of hypertensive disorders of pregnancy and need for neonatal respiratory support). The demonstration of a statistically significant reduction in cesarean and maternal and neonatal morbidity make induction in the 39^th week of gestation an important practice-changing strategy, and has led some to suggest that these are risk-reducing labor inductions and therefore should not be called elective [38]. (See "Induction of labor with oxytocin", section on 'At 39 weeks'.)

Another trial provided level I evidence for a common practice that can be deimplemented for all patients. It is another example of high-quality emerging science that works towards optimizing intrapartum care and positively impacting maternal and newborn morbidity.

●Early rather than delayed pushing – In 2018, a multicenter trial randomly assigned nulliparous patients with neuraxial anesthesia to push when complete dilation is reached or to delay pushing [39]. The cesarean birth rates with early versus delayed pushing were similar: 7.8 versus 7.6 percent, but delayed pushing increased the risk of chorioamnionitis, postpartum hemorrhage, and neonatal acidemia. These findings led to a recommendation from the American College of Obstetricians and Gynecologists (ACOG) to have patients commence pushing when complete cervical dilation is reached [40]. (See "Labor and delivery: Management of the normal second stage", section on 'Early versus delayed'.)

Other strategies are useful in selected patients and represent safe, evidence-based strategies to reduce cesareans for these indications:

●Manual rotation for second-stage dystocia from malposition – Several studies have demonstrated that attempted manual rotation has a high success rate for malposition and is associated with a reduction in cesarean and other maternal morbidities in some studies [41-43]. (See "Occiput posterior position" and "Occiput transverse position".)

●Forceps- or vacuum-assisted vaginal birth for second-stage arrest – Attempted operative vaginal birth by an experienced provider in the appropriately selected patient has a high success rate, thus reducing the need for cesarean birth [44], and the reduction does not come to the detriment of the newborn. Operative vaginal birth, either with forceps or vacuum, has been associated with a low risk of neonatal morbidity, and the risk of intracranial hemorrhage (subdural, cerebral, intraventricular, or subarachnoid) was similar to that with intrapartum cesarean birth in a large study from a California database [45]. Another study using data from New York City hospitals reported a reduced risk of the combined outcome of seizure, intraventricular hemorrhage, or subdural hemorrhage after forceps-assisted birth when compared with vacuum-assisted or cesarean birth [46]. While the cesarean birth rate has been on the rise over the last 15 years, operative vaginal birth rates have declined significantly [47], leading to a reduction in the number of physicians trained in vacuum- and forceps-assisted birth. (See "Assisted (operative) vaginal birth".)

ACOG has provided several additional strategies for safe prevention of the primary cesarean birth, including [48]:

●Antepartum:

•Counseling patients regarding avoidance of excessive gestational weight gain, which is associated with an increased risk for cesarean birth (strong recommendation, moderate-quality evidence). (See "Gestational weight gain".)

•Assessment of fetal presentation at 36 weeks with subsequent external cephalic version of noncephalic presentations to reduce cesarean births performed for this indication (strong recommendation, low-quality evidence). (See "External cephalic version".)

•Encouraging a trial of labor rather than planned cesarean birth for patients with cephalic/cephalic or cephalic/noncephalic diamniotic twins (strong recommendation, moderate-quality evidence). (See "Twin pregnancy: Labor and delivery".)

•Limiting planned cesarean birth to avoid potential birth trauma because of macrosomia to estimated fetal weight ≥5000 grams in patients without diabetes and ≥4500 grams for patients with diabetes (weak recommendation, low-quality evidence). (See "Shoulder dystocia: Risk factors and planning birth of high-risk pregnancies", section on 'Patients with prior shoulder dystocia or estimated weight greater than 4500 or 5000 grams'.)

●Intrapartum:

•Induced labor:

-Use of cervical ripening before induction when the cervix is unfavorable to reduce the risk of failed induction (strong recommendation, moderate-quality evidence). (See "Induction of labor: Techniques for preinduction cervical ripening".)

-Updated definitions for failed induction (allow ≥24 hours for latent phase and administer oxytocin for at least 12 to 18 hours after membrane rupture before diagnosing induction failure) to avoid cesarean birth in the latent phase (strong recommendation, moderate-quality evidence). (See "Induction of labor with oxytocin".)

•Assessment of labor progress:

-Updated definitions of normal labor progress in the first stage and indications for cesarean birth for active phase arrest in the first stage (eg, failure to progress in the active phase [≥6 cm dilation] despite ruptured membranes and four hours of adequate uterine activity [or at least six hours of oxytocin administration with inadequate uterine activity and no cervical change]) to reduce cesarean births in the latent phase and in patients with slow but persistent progress (strong recommendation, moderate-quality evidence). (See "Labor: Overview of normal and abnormal progression" and "Labor: Diagnosis and management of the latent phase" and "Labor: Diagnosis and management of an abnormal first stage".)

-Updated criteria for diagnosis of second-stage arrest before resorting to cesarean birth (strong recommendation, moderate-quality evidence). (See "Labor: Diagnosis and management of a prolonged second stage".)

•Fetal assessment:

-Use of fetal scalp stimulation to assess the fetus with an abnormal or indeterminate fetal heart rate pattern before resorting to cesarean birth (strong recommendation, low-quality evidence). (See "Intrapartum category I, II, and III fetal heart rate tracings: Management".)

-Amnioinfusion to resolve repetitive variable fetal heart rate decelerations before resorting to cesarean birth (strong recommendation, high-quality evidence). (See "Intrapartum category I, II, and III fetal heart rate tracings: Management".)

Many other strategies have been proposed to limit intervention during labor and birth [40] and reduce cesarean birth rates [49-51]. In a 2018 Cochrane review of a wide range of nonclinical interventions aimed at reducing unnecessary cesarean, the following eight interventions had favorable effects [49]. Both randomized trials and nonrandomized studies were included, most were conducted in high-income countries, and many of the results were based on a single small study.

●Childbirth training workshop for mothers (RR 0.55, 95% CI 0.33-0.89; low-certainty evidence)

●Nurse-led applied relaxation training program (RR 0.22, 95% CI 0.11-0.43; low-certainty evidence)

●Psychosocial couple-based prevention program (RR 0.53, 95% CI 0.32-0.90; low-certainty evidence)

●Psychoeducation (RR 0.70, 95% CI 0.49-1.01; low-certainty evidence)

●Implementation of clinical practice guidelines combined with mandatory second opinion for cesarean birth indication (mean difference in rate change RR -1.9, 95% CI -3.8 to -0.1; high-certainty evidence)

●Implementation of clinical practice guidelines combined with audit and feedback (risk reduction -1.8 percent, 95% CI -3.8 to -0.2; high-certainty evidence)

●Physician education by local opinion leaders (obstetrician-gynecologist; elective cesarean rate: 43 percent with the intervention versus 67 percent with usual care; high-certainty evidence)

●Collaborative midwifery-laborist model of care (odds ratio [OR] 0.56, 95% CI 0.39-0.81; low-certainty evidence)

Another Cochrane review noted that continuous one-to-one support during labor decreased cesarean birth when epidural analgesia was not routinely available (average RR 0.54, 95% CI 0.41-0.72) but did not make a clear difference when epidural analgesia was available (average RR 0.91, 95% CI 0.81-1.02; low-certainty evidence) [52]. (See "Labor and delivery: Management of the normal first stage" and "Labor and delivery: Management of the normal second stage" and "Continuous labor support by a doula".)

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Cesarean birth".)

SUMMARY AND RECOMMENDATIONS

●Definition and determination – We define the optimal cesarean birth rate as the rate that minimizes maternal and neonatal morbidity and mortality coupled with maximal maternal satisfaction. This rate is not known and likely varies by patient population. Rates below 15 to 20 percent have been associated with increased maternal and/or perinatal morbidity. When determining cesarean birth rates, it is useful to calculate the rate in groups of similar risk using a system such as the Robson classification and account for maternal and perinatal outcomes. (See 'How should cesarean birth rates be measured and what is optimal?' above.)

●Selected strategies for reducing cesarean rates higher that the optimal rate – Hospital systems and individual providers should be aware of their cesarean birth rate and adopt evidence-based clinical management strategies that minimize maternal and neonatal morbidity and mortality and maximize maternal satisfaction. These strategies may include but are not limited to (see 'Selected strategies for safe reduction of the cesarean birth rate' above):

•Avoidance of excessive gestational weight gain

•Use of cervical ripening before induction when the cervix is unfavorable

•Antenatal external cephalic version of noncephalic presentations

•Trial of labor for cephalic/cephalic or cephalic/noncephalic diamniotic twins

•Induction at 39^th weeks of gestation

•Avoidance of cesarean births in the latent phase and in patients with slow but persistent progress in the first stage

•Avoidance of cesarean births in the second stage in patients with slow but persistent progress

•Amnioinfusion to resolve repetitive variable fetal heart rate decelerations

•Use of fetal scalp stimulation to assess the fetus with an abnormal or indeterminate fetal heart rate pattern

•Avoidance of delayed pushing

•Manual rotation for second-stage dystocia from malposition

•Forceps- or vacuum-assisted vaginal birth for second-stage arrest in the appropriately selected patient

•Collaborative midwifery-laborist model of care