1. Introduction

The Maternity Outcomes Signal System (MOSS) was developed by NHS England in response to the East Kent Reading the signals report.

The report recommended the development of a safety signal system capable of monitoring routinely collected maternity and neonatal outcomes to detect potential declines in safe care in a timely way.

MOSS operates at trust site level. It is a near-real time safety signal system that supports early detection and rapid responses to potential safety issues in intrapartum care service delivery.

Safety signal systems are widely used in healthcare and other high-risk industries to monitor outcomes and processes to prompt rapid safety checks and initiate early interventions when unusual patterns occur.

Examples include children’s cardiac services and paediatric intensive care, which use cumulative sum control chart methodology (CUSUM) – a statistical analysis used to detect trends in rare but serious events to improve mortality and morbidity outcomes.

MOSS applies this approach to maternity with a specific focus on intrapartum care safety.

MOSS is not a performance management or investigation tool; it is part of a wider critical safety management system (CSMS). Together, these systems are essential tools that help organisations deliver consistently safe care.

Signals do not necessarily mean that a service is unsafe, but prompt a service-led critical safety check: providing early insights into potential intrapartum care safety issues and enabling rapid intervention to reduce harm.

MOSS operates within the perinatal quality oversight model (PQOM), ensuring consistent monitoring, support, and escalation across trusts, ICBs, regions, and nationally.

MOSS was developed collaboratively with pilot trusts, clinicians, service users, and national organisations including MBRRACE-UK, MNSI, NHS Resolution, and NHS England’s Patient Safety Team.

MOSS has also had input from Dr Bill Kirkup, author of the East Kent report, and Professor David Spiegelhalter, a recognised expert in statistical risk.

Scope of the standard operating procedures and other guidance

These standard operating procedures explain the responsibilities of trust boards and maternity services, ICBs, regions and the national team in relation to MOSS.

This includes carrying out a critical safety check in response to a signal (Annex 1) and how the output of the response is governed under PQOM.

There is additional guidance provided separately to support the successful implementation of MOSS:

• A user guide on how to access MOSS (Annex 2)
• A user guide on how to interpret the charts in MOSS (Annex 3)
• Statistical methodology and data sources (Annex 4)
• Frequently asked questions on MOSS (Annex 5)
• Example of a standard escalation of a MOSS critical safety check in the Perinatal Quality Oversight Model (Annex 6)
• Contextual background on the use of signalling tools (Annex 7)
• Glossary of terms (Annex 8)

Purpose of MOSS

MOSS is a safety signal system. Its objectives are to:

• be sensitive and specific to services that deliver intrapartum care by using term outcome measures (term stillbirths and term neonatal deaths up to 28 days) that have a high potential of causation from care and service delivery issues and a low index of causation from known clinical conditions
• identify unusual near-real time changes in outcome trends that may indicate declining intrapartum safety
• prompt a critical safety check led by the local perinatal leadership team to assess the safety of operational processes on the labour ward, review priorities, and plan early interventions; the perinatal leadership team includes:
  • the obstetric lead (clinical director or head of service)
  • neonatal lead (nursing or medical)
  • director of midwifery (or head of midwifery, if none appointed)
  • the operational lead of the maternity service.
• support rapid escalation through trust, ICB, regional, and national PQOM structures if safety issues are identified
• support a positive safety culture
• improve outcomes

2. MOSS methodology

MOSS uses CUSUM methodology, which is able to analyse rare events, set thresholds and generate signals if trend changes cross these thresholds.

The CUSUM chart in MOSS helps track whether there are more adverse events than expected at a maternity unit. It compares the actual number of events to the number we would normally expect based on national data.

Signal levels

• Amber signal (Level 1): There is a 95% chance that the increase in events is real and not due to random chance.
• Red signal (Level 2): There is a 99% chance that the increase is real. After a red signal, the system resets so it is sensitive to future increases in events and can signal quickly.

Thresholds

1. The national average number of events is calculated on a 3-year rolling basis from recent data.
2. The expected number of events for each trust site is calculated based on the number of births at the site.
3. An ‘increase in events’ is defined as at least twice the expected number.
4. The CUSUM keeps adding the difference between actual events and expected events over time.
5. When this total passes the amber or red threshold, a signal is generated.

Key features of MOSS

MOSS has several key features to support identification of signals, timely action and escalation:

• MOSS uses existing data from the personal demographic service to derive term stillbirths and term neonatal deaths up to 28 days. In 2026, data on hypoxic ischaemic encephalopathy (HIE) at grade 2 or 3 will be included from the Submit a Perinatal Event Notification service (SPEN).
• Data is timely and refreshes daily, generating signals immediately.
• Automated email alerts are sent to users immediately once a signal is generated.
• MOSS is viewable at trust, ICB, regional, and national levels. An NHS England public-facing national report will also be published twice per year to ensure transparency.

3. Pre-requisites to implement MOSS

To implement MOSS effectively, maternity services must establish the following:

Access to MOSS and operational data

1. Registration – at a minimum

• Perinatal leadership teams
• Accountable trust board executives:
  • chief nurse
  • chief medical officer
  • executive trust board safety champion
• Maternity and neonatal voice partnership leads (as defined in 5.1.4 of PQOM)
• Maternity improvement advisors
• The ICB executive with responsibility for maternity and neonatal services
• ICB director of quality
• Regional chief nurse
• Regional chief midwife
• Regional chief obstetrician
• Regional medical director

Other trust, ICB, regional and national colleagues with a remit over supporting perinatal quality or governance should also register for access.

A guide to accessing MOSS is in Annex 2.

2. Data access

Establish how to access the required data for the critical safety check (Annex 1).

Routine use

3. Monitoring

Trust site maternity teams should check MOSS (and the MBRRACE-UK Real Time Data Monitoring Tool) at least monthly for discussion at perinatal quality meetings.

This is required to maintain an awareness of outcome trends and preparedness for a response, particularly when outcomes are close to crossing signal thresholds.

4. Testing

Perinatal leadership teams should practice at least one annual drill using the critical safety check.

5. Psychological safety

The process must operate in a culture of openness and trust, enabling staff to share information without fear of blame.

6. Addressing known and emerging safety themes

Perinatal leadership teams should be addressing themes from reports and feedback with trust board oversight (see ‘assumed knowledge/processes in place’ in Annex 1).

Pathways for rapid review and escalation

7. Escalation pathways

Define rapid communication pathways to complete the critical safety check within 8 working days.

This is particularly relevant to communication between perinatal leadership teams, labour ward staff, accountable trust board executives and external peers (with level 2 signals).

8. Peer review

For level 2 signals, an external peer must be selected by perinatal leadership teams to check and challenge the completed critical safety check within 8 working days from the signal.

External peers must be from outside the trust and can include maternity improvement advisors (where a trust is already entered onto the Maternity Safety Support Programme) or ICB or regional colleagues involved in perinatal quality oversight.

Governance

9. Alignment with PQOM

Roles, responsibilities, and escalation routes should follow the perinatal quality oversight model.

National support

Colleagues in the national Maternity and Neonatal Programme team will support trusts, ICBs and regions to implement MOSS.

30-minute support sessions can be booked, and are available every Monday between 1.30pm and 3pm.

Time will be prioritised to services who have received a signal from MOSS.

It is important that maternity services attempt the critical safety check (Annex 1) immediately following a signal. Please do not wait for a meeting to be arranged first.  

For queries, or to book a support session, please contact england.moss@nhs.net.

For technical queries on accessing MOSS, contact england.datavizfunction@nhs.net.

4. Roles and responsibilities of organisations with MOSS

Use of MOSS must fit within existing PQOM governance structures, as below. An example of a standard escalation of a MOSS critical safety check is also described in Annex 6.

Trust boards and maternity services in trusts are responsible for local maternity service quality and safety.

Responsibilities of maternity services in trusts include:

• monitoring MOSS monthly and discussing at service level perinatal quality meetings
• ensuring MOSS pre-requisites are in place (pages 5 and 6)
• perinatal leadership teams completing critical safety checks through co-production with staff working on the labour ward
• in all signals – perinatal leadership teams sharing completed checks with an accountable trust board executive (the chief nurse, the chief medical officer or the executive trust board safety champion) for approval
  • at least 1 accountable trust board executive must approve the completed check within 8 working days of a signal
• in level 2 signals only – perinatal leadership teams sharing completed check with external peers for review before approval from accountable trust board executives
• perinatal leadership teams sharing approved critical safety checks with ICB and regional colleagues within 8 working days of a signal, even if no safety issues are identified
  • ICB colleagues include the ICB executive with responsibility for maternity and neonatal services and the director of quality
  • regional colleagues include the regional chief nurse, midwife, obstetrician and medical director
• deputies: members of the perinatal leadership team may deputise for one another to lead on completing the check in the event of leave/sickness
  • accountable trust board executives may deputise for one another to provide approvals

The responsibilities of trust boards include:

• accountable trust board executives should inform the trust board of safety issues found from critical safety checks, which should be discussed as an agenda item at the next public trust board meeting
  • accountable trust board executives include the chief nurse, chief medical officer and executive trust board safety champion
• trust boards should provide oversight and active engagement to ensure that any plans made to address safety issues make progress and are completed at the required speed

ICBs (note – these responsibilities do not apply if regions have successfully transitioned to the new Model Region Blueprint – see above note): Oversee the quality of maternity services, system-wide. Responsibilities include:

• the ICB executive with responsibility for maternity and neonatal services, ensuring trusts respond to signals and fostering a culture of psychological safety
• receiving completed safety checks and supporting trusts to address issues
• escalating unresolved or serious issues to regional teams
• ICBs continue to manage clinical quality risks in line with the National Quality Board guidance on risk response and escalation

Regions who have not transitioned to the Model Region Blueprint: NHS England regional teams oversee ICBs and provide additional support. Responsibilities include:

• promoting an open culture and psychological safety
• reviewing escalated safety issues and determining if national escalation is required

Regions who have transitioned to the Model Region Blueprint: NHS England regional teams oversee the quality of maternity services region-wide. Responsibilities include:

• regional chief nurses ensuring trusts respond to signals and fostering a culture of psychological safety
• receiving completed safety checks and supporting trusts to address issues
• escalating unresolved or serious issues to the national team
• facilitating rapid quality reviews in line with National Quality Board guidance.

National team: The National Perinatal Surveillance Group (NPSG) meets every 6 weeks and is the highest escalation point. Responsibilities include:

• sharing intelligence, monitoring organisations and tracking outcomes
• reviewing escalated issues and determining further actions, such as referral to the Maternity Safety Support Programme

Publication reference: PRN02098_i