What is a neonatal unit?
A neonatal unit is a hospital ward for newborn babies who need medical care beyond a normal post-natal ward. Some are born too early (“preterm”). Some are born at term but sick or injured in birth. A neonatal intensive care unit (NICU) is the most intensive kind — for the smallest and sickest babies.
Babies on a neonatal unit are almost always in transparent-sided incubators or on open-topped resuscitaires. They are monitored continuously: oxygen saturation, heart rate, respiratory rate, temperature, often blood pressure. Monitors alarm constantly — nurses manage a continuous flow of alerts that are usually trivial and occasionally critical.
Levels of care (Level 1, 2, 3)
UK neonatal units are classified into three levels:
- Level 1 — Special Care Baby Unit (SCBU). The lowest tier. Appropriate for babies who need observation, tube-feeding, low-flow oxygen, phototherapy. Not equipped for ventilation of extremely preterm infants.
- Level 2 — Local Neonatal Unit (LNU). Middle tier. Can provide short-term intensive care, including mechanical ventilation, for babies born from around 27 weeks. Not designed as a long-term home for 23- or 24-week infants, who should be transferred out to a Level 3 unit.
- Level 3 — Neonatal Intensive Care Unit (NICU). The highest tier. Full intensive care for the smallest (22–26 week) and sickest babies. Has surgical, cardiology and specialist ventilation back-up.
Why this matters in the Letby case: the Countess of Chester neonatal unit was a Level 2 unit. Several of the infants on the indictment were below the gestation the unit was designed to care for long-term. Independent reviewers argue this designation mismatch is itself a substantial explanation for the mortality pattern. See our evidence page on unit conditions.
Why gestation is everything
Gestational age — the number of weeks a baby has been developing in the womb — is the single biggest predictor of neonatal outcome. Survival and disability rates change dramatically with each week. A very rough sense of scale:
- 22 weeks: edge of viability. Survival is rare even with perfect care; severe disability the expected outcome if the baby survives.
- 23–24 weeks: survival possible but uncertain; severe disability common. Expected course: multiple serious deteriorations requiring aggressive intervention.
- 25–27 weeks: survival more likely; moderate-to-severe complications still common, including brain bleeds, lung disease, and necrotising enterocolitis.
- 28–32 weeks: generally survive; the complications are milder but still serious.
- 33–36 weeks: often do well; usually shorter neonatal-unit stay.
- Term (37+ weeks): most problems are acute (birth injury, infection) rather than developmental.
Why this matters in the case: Child K was a 25-week infant. Child G was around 23 weeks. At those gestations, episodes the jury was told were the consequence of deliberate harm are episodes neonatologists would expect to see without any wrongdoing at all.
Lines, tubes, and why they move
A premature baby on a neonatal unit will typically have:
- An endotracheal tube (ET tube) if mechanically ventilated — a plastic tube running through the mouth or nose into the windpipe.
- A nasogastric (NG) tube through the nose into the stomach for feeding.
- An umbilical venous catheter (UVC) or long line for intravenous medication and fluids.
- CPAP prongs in the nostrils if receiving pressurised oxygen but not intubated.
These items move. UK neonatal guidance is explicit about this: whenever a preterm baby deteriorates unexpectedly, the first thing the nurse or doctor must consider is whether the tube has moved. ET tubes in particular are easy to dislodge in very small babies. Spontaneous dislodgement is not a red flag — it is the expected default assumption.
Why this matters: the Child K conviction depends on treating an ET-tube dislodgement as evidence of attempted harm, in a 25-week infant where that event is routine.
Feeding a premature baby
Premature babies are fed through a nasogastric tube, or intravenously via Total Parenteral Nutrition (TPN) — a mixture of glucose, amino acids, lipids and electrolytes prepared in a hospital pharmacy. TPN bags hang on drip stands; pharmacy errors in formulation are not unheard of and are a well-recognised cause of electrolyte disturbances on neonatal units.
Feed volumes depend on gestation and weight. There is no single “correct” volume; neonatal practice uses published tolerance ranges and adjusts up or down based on how the baby tolerates each feed. Aspiration — where feed is regurgitated and inhaled — is a recognised risk, especially in very preterm babies with poor gag reflex.
Why this matters: the Child G conviction alleged over-feeding causing aspiration; the Panel considers the feed volumes cited at trial within the range observed for that gestation.
What a neonatal collapse actually looks like
A neonatal “collapse” is not a single event with a single cause. It’s a sudden deterioration in a sick baby, and it can look very similar regardless of the underlying cause. Typically: sudden drop in oxygen saturation, rapid or slow heart rate, pale or mottled skin, loss of tone. The response is the same regardless of cause: assess airway, ventilate, give chest compressions if needed, call a senior clinician.
Skin mottling during a collapse is a non-specific sign. It happens in sepsis, in shock, in cardiac failure, in severe NEC, in late-stage intracranial haemorrhage. Telling one cause from another, just from the skin pattern, is not reliably possible. That is the heart of the dispute about the air-embolism claim — see our air-embolism evidence page.
NEC, sepsis, IVH: the natural killers
Three conditions account for most unexpected deaths on neonatal units:
- Necrotising enterocolitis (NEC). A devastating bowel disease of premature babies in which parts of the gut wall become inflamed and necrotic. Can produce sudden collapse with gas in unusual places on abdominal X-rays — precisely the kind of X-ray finding the prosecution interpreted differently in some counts.
- Sepsis. Bloodstream infection. Premature babies have immature immune systems. Sepsis can progress from mild to fatal in hours. Skin mottling is classic.
- Intraventricular haemorrhage (IVH). Bleeding in the fluid-filled spaces inside the brain. Very common in extremely preterm infants. Can cause sudden deterioration, apnoea, or seizures.
Any of these can look, to a lay observer, like a sudden unexplained collapse. The expert task is to distinguish which is which. That task is harder than it seems, which is why the Panel thought it was worth doing it again, case by case, with fresh eyes.
Staffing and workload
Neonatal units run tight ratios: typically one nurse to one very sick baby (“1:1”) for Level 3 intensive care, one nurse to two babies for Level 2 (“1:2”), one to four for Level 1. When a unit is short-staffed — as the Countess of Chester was documented to be during 2015–16 — these ratios stretch. Stretched ratios mean alarms take longer to respond to, routine checks slip, and the whole margin for picking up the kind of early deterioration warning that prevents a collapse shrinks.
Systems like Datix (the NHS incident-reporting system) exist to log the kind of equipment failures, medication errors and near-misses that build up when a unit is stretched. The Thirlwall Inquiry has examined the Datix record for the unit; the picture is of a unit operating beyond its safe envelope.
How neonatal records work
Neonatal care generates vast amounts of paperwork per baby per shift. At minimum there will be: continuous monitor trend charts, hourly observations, feed charts, medication charts, ventilator settings, blood-gas results, fluid balance, and the doctor’s daily review. A handover sheet is a nurse’s personal summary at the start of a shift — often a printed or photocopied page that the nurse annotates through the shift.
Why this matters: handover sheets found at Letby’s home were held up at trial as suspicious. In fact, keeping handover sheets at home is a documented neonatal- nursing practice — for continuing professional development, reflective logs, or just because the nurse ran out of time at the end of a shift. See our handover-notes evidence page and our police-interviews summary.
Takeaway
A neonatal unit is an environment where very bad things happen to very small, very sick babies, without anyone doing anything wrong. That is the baseline. To establish deliberate harm against that baseline requires evidence that is specific to deliberate harm — not evidence that is compatible with it but also compatible with natural causes.
The Panel’s case-by-case conclusion — that in every indicted case, the evidence is compatible with natural causes — is, for a neonatologist, a serious claim. Whether the Court of Appeal ultimately accepts it is a legal question that only the Court of Appeal can decide. But it is not a lay or fringe view. It is the view of fourteen senior neonatologists who have spent their careers on units like the Countess of Chester’s.