MNSI data shows a fall in reported cases of HIE in England

MNSI (Maternity and Neonatal Safety Investigations) have today announced a significant and encouraging trend: a reduction in reported cases of Hypoxic-Ischaemic Encephalopathy (HIE) in England over the past five years. HIE is a condition I see in my work as every day as Head of our firm's Obstetric Division.

It is a critical neonatal condition caused by oxygen deprivation and restricted blood flow to the brain and remains a leading cause of neonatal mortality and long-term disability, including cerebral palsy.

Understanding the scope of MNSI reporting

The MNSI focuses its investigations on term babies (over 37 weeks gestation) whose mothers have been in labour, and who are diagnosed with potential severe brain injury within the first seven days of life. The criteria for inclusion are stringent, involving therapeutic cooling or clinical signs of moderate to severe encephalopathy. It is important to note that not all UK cases of HIE are captured by MNSI, as their remit excludes preterm infants and those outside the specified clinical parameters.

Our obstetric division follows MNSI reporting closely as these issues are highly relevant to our case work and assistance to Trust clients. Crucially, MNSI investigation outcomes help our NHS Trusts to align their practices with the findings and recommendations derived from real-world investigations, promoting a proactive culture of safety and quality care in maternity services.

We comment further on the MNSI’s safety investigation, with articles on our maternity resources hub.

Key findings from the data

The data shows a steady decline in referrals for potential severe brain injury, from 657 cases in 2020/21 to 431 in 2024/25. Confirmed severe brain injuries, as evidenced by MRI scans or ongoing neurological symptoms, also fell from 248 to 138 in the same period. While the birth rate has declined, the reduction in HIE referrals exceeds what would be expected solely from fewer births, suggesting genuine progress in preventing HIE.

Crucially, this reduction has not coincided with an increase in intrapartum stillbirths or early neonatal deaths which could otherwise mask the true incidence of HIE. These outcomes have remained static or decreased, reinforcing the positive trend.

Possible causes and implications

Whilst there could be a range of reasons which explain the positive fall in numbers, improvements in maternity and newborn care, supported by learning shared through MNSI and its predecessor, the Healthcare Safety Investigation Branch, may be contributing factors. Enhanced clinical practices, better monitoring during labour, and wider adoption of therapeutic hypothermia (as recommended by the British Association for Perinatal Medicine, based on the TOBY study) are also likely playing a role.

What the fall in HIE cases means for maternity safety – and what comes next

Acknowledging that any case of avoidable HIE is one too many and although only relating to data in England, in an environment where there is so much negativity in terms of maternity care, the fall in reported HIE cases in England is a positive and welcome development.

The data suggests that improvements in intrapartum monitoring, the broader adoption of therapeutic hypothermia, and the dissemination of learning through MNSI and HSIB investigations are beginning to translate into better outcomes at the bedside. This is what a culture of safety, accountability, and continuous improvement looks like in practice. Reflecting advances in clinical care and safety, continued vigilance, learning, and improvement will be essential to sustain this trend and ensure the best possible outcomes for mothers and babies.

What NHS Trusts should do now

The positive trend does not reduce the imperative for Trusts to remain vigilant, if anything, it raises the bar. Based on our experience advising NHS Trusts and healthcare organisations on maternity safety, we would encourage the following:

1. Review your HIE governance frameworks in light of MNSI's latest findings. Are your incident review processes capturing the right cases, and are learning outcomes being embedded in clinical practice?
2. Audit compliance with BAPM therapeutic hypothermia guidelines to ensure consistent application across your unit, including out-of-hours scenarios.
3. Scrutinise your intrapartum monitoring protocols: Enhanced CTG interpretation and escalation pathways remain one of the most impactful levers for reducing preventable HIE.
4. Engage proactively with MNSI investigation outcomes relevant to your Trust, and ensure findings are translated into tangible changes rather than filed away.
5. Consider the medico-legal risk landscape: A reduction in HIE incidence does not mean a reduction in claims complexity. Cases involving HIE remain among the most high-value and high-stakes in clinical negligence litigation, and early expert advice is essential.

The role of legal support in maternity safety

Trusts that take a proactive, rather than reactive, approach to maternity governance (including engaging legal advisers early when incidents occur) are better placed to manage risk, support families appropriately, and drive lasting improvement.

If you advise or work within an NHS Trust or healthcare organisation and want to understand how the MNSI data affects your legal exposure or governance obligations, our specialist maternity team is here to help. We work closely with maternity and neonatal teams across England, advising on everything from individual HIE claims to Trust-wide safety improvement programmes.

The fall in HIE cases is progress, but the work is far from over. Sustained improvement requires ongoing investment in clinical excellence, robust governance, and the right legal and advisory support.