Table 4.

Description of included interventions

Study	Intervention	Details
a) Financial interventions
Health worker payment methods
Lo 2008 [22]	Increase physician fees for vaginal birth after caesarean (VBAC) fee to the same level as caesarean section Increase in vaginal birth physician fees to that of caesarean section	National Health Insurance Taiwan equalised the fee for VBAC to that of a caesarean in April 2003. In May 2005, the fee for vaginal birth was raised to the equivalent of that of a caesarean section.
Keeler 1996 [23]	Equalising physician fees for vaginal and caesarean delivery	Revision to fee schedule for obstetric and other procedures including equalising the fees for vaginal and caesarean sections.
Liu 2007 [24]	National Health Insurance (NHI)	National Health Insurance (NHI) which equalized price for CS and vaginal delivery implemented in 1995.
Health organization payment methods
Diagnosis-related group payment system
Kim 2016 [25]	Diagnosis-related Group (DRG) payment system	Diagnosis-related Group (DRG) payment system with fixed reimbursement for physicians regardless of cost of CS procedure. To promote vaginal delivery, the medical fee for vaginal birth increased by 50%, raising per diem profits above those of CS delivery and additional reimbursements were given for vaginal delivery of a patient over 35.
Lee 2007 [26]	Diagnosis-Related Group (DRG) payment system.	Diagnosis-Related Group (DRG) prospective payment system (PPS) which sets a fixed fee for service. In a DRG group, the fee difference between CS and vaginal delivery is less than in a fee-for-service (control) system (in the DRG system the fee for CS was less than 2 times that for vaginal delivery. In the fee-for-service, the fee for CS was 2.7 times that for vaginal delivery). Three set DRG codes: CS, vaginal delivery with complication, vaginal delivery without complication. The fee for a set code is determined by the severity of complication/comorbidity index.
Global budget payment (GBP) system
Chen 2014 [27]	Global fee for obstetric services, increasing reimbursement for vaginal delivery to be equal to CS Co-payment when CS not indicated	Policy I: Financial incentives to encourage vaginal delivery through a global fee for obstetric services and increasing reimbursement for vaginal delivery to be equal to that of caesarean sections. Policy II: Copayment when caesarean section is not medically indicated (aimed to reduce the demand for elective caesarean procedure).
Kozhimannil 2018 [28]	Global fee for uncomplicated deliveries (regardless of mode)	Single blended payment rate for uncomplicated births (regardless of mode of delivery). Before the policy, facility fees were $3144 and $5266 for uncomplicated vaginal and caesarean births, respectively. As of October 1, 2009, the policy changed the rate to $3528 for uncomplicated births, regardless of mode of delivery.
Liu 2013 [29]	Global Budget System Hospital-based Self-Management (HBSM)	Global Budget System (GBS) in July 2002. This entails direct government funding for hospitals and by extension cost-reduction and elimination of unnecessary services. Hospital-based Self-Management (HBSM) in August 2005 involves post-operative peer reviews and audits to reduce medical service costs incurred by CS.
Case-based payment system
Tsai 2006 [30]	Vaginal birth after caesarean section (VBAC) case payment program	Vaginal birth after caesarean section (VBAC) case payment program introduced by Taiwan’s Bureau of National Health Insurance (BNHI).
Cap-based payment system
Misra 2008 [31]	Cap based payment system	The HealthChoice managed care program (mandatory for Medicaid recipients, and have risk-adjusted capitation rates designed to individualize care and reduce unnecessary CS rates.
Chen 2016 [32]	Cap-based maternity insurance scheme (MIS)	Cap-based maternity insurance scheme (MIS) • Limits unnecessary expensive procedures by not reimbursing hospitals above price of cap. Patients no longer pay upfront. The cap system does not reimburse hospitals for costs above the threshold (per capita) which disincentivizes doctors from prescribing unnecessary procedures.
Other financial interventions
Karami 2018 [33]	Financial incentive and free vaginal delivery policy	Financial incentive and free vaginal delivery policy • Health Sector Evolution Plan (HSEP) reform provided free-of-charge inpatient services for vaginal delivery and offered financial incentives for providers to promote vaginal rather than CS delivery.
b) Regulatory and legislative interventions
Studnicki 1997 [34]	Legislatively imposed practice guidelines	Legislatively imposed practice guidelines • Mandated that practice guidelines regarding caesarean section deliveries be disseminated to obstetric physicians. • The law also required that peer review boards at hospitals be established to review caesarean deliveries and that the exact dates of implementation of the guidelines be reported to a state agency. The provider hospitals were required to provide copies of the guidelines to obstetric physicians and other persons appropriately credentialed to perform caesarean deliveries, establish a peer review board to review caesarean deliveries and ensure that its findings are shared, incorporate the peer review board reviews and reports into the hospital’s quality assurance monitoring and peer review process, and to report to the state Agency for Health Care Administration (AHCA) the dates of the implementation of the practice parameters and the initial meeting of the peer review board.
Yu 2017 [35]	Multifaceted institutional and policy interventions.	Institutional interventions Health education (face-to-face weekly educational meetings between patients and hospital staff, training for obstetricians and midwives) painless delivery introduction, and doula care. Policy interventions 1. Development plans • The Regulation for the Management of Maternal Health Care and the Norms of Maternal Health Care Encourage mothers to choose vaginal delivery; Should strictly control indications for caesarean section (CS); Should strictly control caesarean delivery on maternal request (CDMR). • The Project of Maternal and Child Health During the 12th 5 Year Plan in Zhejiang Province Reduce the CS rate in Zhejiang Province. • The Development Plan for Women in Wenzhou Enhance health education about maternal health; Popularize knowledge about perinatal health care; Reduce the CS rate in Wenzhou area. 2. Evaluation criteria Medical Quality Management and Control Indicators for Tertiary Comprehensive Hospitals. The CS rate was included among patient safety indicators.
c) Other interventions
Snowden 2016 [36]	Oregon “hard-stop” policy limiting elective inductions and caesarean deliveries before 39 weeks of gestation	Oregon “hard-stop” policy limiting elective inductions and caesarean deliveries before 39 weeks of gestation. Introduced by the Oregon Perinatal Collaborative in 2011. The hard-stop policy limited early-term deliveries by requiring review and approval for any delivery without documented indication before 39 weeks of gestation (in contrast with other approaches, e.g., “soft-stop” policies, which give providers more discretion).
Borem 2020 [37]	Quality improvement initiative: “Appropriate Birth”	Quality improvement initiative: Projeto Parto Adequado (PPA) or “Appropriate Birth.” comprised of four change packages: 1. Leadership Coalition of major stakeholders aligned around primacy of safe mother, safe baby.
		Drivers of change	Change concept
		Alignment of financial incentives to hospitals and health plans. Drive change and remove barriers to create a learning and culture improvement. Engaged, activated community expecting best, safest care.	Leaders, champions, front line with the skills to do continuous improvement. Educate senior leaders, providers, community and patients about the benefits of physiologic birth. New contract between payers and providers creating incentives for quality and safety. New contract between health plan/hospital creating incentives for quality, safety and normal birth. Activate the community.
		2. Pregnant women Empower pregnant women and their families to choose the care that is right for them (ensure readiness for normal birth).
		Drivers of change	Change concept
		Adequate information, based on evidence to support the best choice. Co-design and shared decision. Retake ownership of labor.	Educate and instruct families and pregnant women to new care model. Public campaigns. The intangible aspects of being a mother - delighting the pregnant women and families. Listening to mother and families.
		3. Healthcare system New care model to accommodate the longer time frame of normal physiologic birth.
		Drivers of change	Change concept
		Perinatal redesigning. Confident and competent caregivers can support natural birth. Supportive environment for clinicians promotes “joy in work”. Shared care for mother-child unit. Reliable implementation of best clinical practice	Protocols and standardization for perinatal care. Physical space redesign (Ambiance for normal birth – Delivery Rooms). Invest resources to conquer healthy work environment. Well trained team to assist the deliveries. Multi-professional team assisting all pregnancy phases. Protocols and standardization for delivery and postpartum.
		4. Information Data systems that support learning.
		Drivers of change	Change concept
		Transparency. Select measures to reflect quality and safety.	Create the capability to collect reliably information - measures and results. Feedback to professional teams, patients and families. Establish some quality and safety measures, report them to the providers and general public.