Lucy Letby – an obstetric view

Background

I am emeritus professor of obstetrics & gynaecology at the University of Nottingham and, until I retired in 2024, was a consultant obstetrician at Nottingham University Hospitals NHS Trust. www.ripe-tomato.org is my blog

A year ago I read A British Nurse Was Found Guilty of Killing Seven Babies. Did She Do It? by Rachel Aviv in the New Yorker (click here). The baby K retrial was ongoing, and the courts had blocked the UK online version, but I had a paper copy.

Aviv argued that no-one witnessed Letby attacking any baby, and that the apparently incriminating notes containing the words, “I am evil”, “I killed them”, were neither a confession nor incriminating, when read in their entirity.

There had been a spike in deaths, but the Countess of Chester hospital had other problems, and the mortality fall after she was removed from clinical duties, coincided with the hospital ceasing to care for the sickest babies.

Letby seemed to have been convicted largely on the basis of being the only person present when all the suspicious events occurred, but statisticians Aviv spoke to, suspected that the events had been selected because she was present, the so called Texas Sharpshooter fallacy.

The main prosecution expert had offered his services to the police, had little up-to-date expertise in neonatology, and seemed more keen on helping get a conviction, than as acting as an independent advisor to the court. His theory that some deaths had been caused by air embolism was based on a misunderstanding of the paper he cited.

When the police were alerted to the possibility that there might be a multiple murderer active in the neonatal unit, they had allowed the accusing medical staff, against whom Lucy had recently had a claim of bullying upheld, to lead the search for evidence, rather than including them in the list of suspects.

The two insulin cases, which the prosecution argued proved that there was a poisoner in the unit, were based on a tricky insulin/c-peptide assay done by a non-accredited lab. The results had been ignored at the time, and the babies recovered, so they couldn’t be rechecked. Letby was not charged for a third insulin case of which the defence was unaware. Aviv argued that these weak insulin cases dragged the rest behind them, in the “belief that all the deaths couldn’t have occurred by chance”.

I’m not a true crime buff, nor a miscarriage of justice campaigner, but the article disturbed me. The New Yorker doesn’t usually get stuff wrong; it’s rather famed for its obsessive fact checking. Since then more information supporting Aviv’s concerns has come to light.

The incriminating notes may have been written on the advice of a counsellor while Letby was suspended for alleged incompetence and felt bullied.

Professor David Spiegelhalter has explained to the Thirwall inquiry that the spike in deaths was not outside what might easily arise in a relatively poorly run unit (click here).

We now know, what the statisticians had suspected, that many events and deaths had first been labelled suspicious on the basis of Letby’s presence, and that others were discarded if she was absent (click here).

Hardly a month goes by without new problems appearing around the insulin evidence.

In the only case (Baby K) where Letby was witnessed doing anything, namely standing doing nothing over a desaturating baby, the witness, Dr Jayaram, had made no note at the time, not even privately to his colleagues, despite them all already suspecting she was a murderer. Instead an email has recently come to light (click here) in which he had written, apparently contradicting his later sworn testimony, that Letby had called him into Baby K’s room.

But far more important than any of that, in February this year, an international expert panel, convened by Professor Shoo Lee, the expert whose research had been misunderstood, identified straightforward non-malicious explanations for all the deaths and collapses. “We did not find any murders”. Click here.

I’m not going to go over all the Shoo Lee panel’s arguments here, but the air embolism misunderstanding is not complicated.

Air accidentally entering a pulmonary vein, the topic of the misquoted Lee and Tanswell paper (click here), passes into the systemic circulation and, when it reaches the skin capillaries, may cause a specific skin rash. In contrast air injected into a peripheral vein¹, the act Letby was accused of, has to first pass through the lung capillaries where it will be trapped. Anyone who knows the difference between an artery and a vein, and has got their head around William Harvey’s discovery of the blood circulation, can understand the difference.

Shoo Lee himself caused a potential confusion by mentioning the theoretical possibility that injected peripheral vein air could pass through the foramen ovale, a normal hole in the heart to reach the systemic circulation and the skin. He dismissed this possibility in practice, because the foramen ovale closes at birth, and even in the rare cases where it does not, the pressures on the different sides of the heart after birth would prevent air bubbles flowing in that direction. Every obstetrician and neonatologist knows all about the transition from the fetal to the adult circulation at birth, so knows that Shoo Lee is correct. Finally, to remove any last doubt, Shoo Lee wrote another paper last year looking specifically for reports of patchy skin discoloration in infants with peripheral venous air embolism (click here). There have been zero such reports.

But none of this new evidence has been tested in court. Letby has already been refused two appeals and will spend the rest of her life in prison unless the Criminal Cases Review Commission (CCRC), decides to take her case on.

In the meantime, although almost all doctors I’ve discussed the case with have serious doubts, relatively few have come out publicly in Letby’s defence.

The reason is probably that few working doctors have time to read all the details, and it’s risky publicly defending a convicted child killer. One of the few practicing neonatologists to speak out has had people complain about her to the GMC and to her employer.

I retired last year, so I’ve got the time and don’t really care if people write to the GMC about me. But I’m not a neonatologist, nor even a paediatrician, so what can I add?

I was an NHS obstetrician for over 40 years, and in clinical practice in 2015/16, when the events unfolded. Since no obstetrician appears to have commented on the case in detail, I’m going to try and fill that gap, and focus on the maternal aspects, the obstetrics.

My plan is to collect what information I can about the pregnancies of each mother, and provide a brief obstetric commentary. Since I’ve not got access either to the mother’s notes, nor to the trial transcipt, I will rarely be able to come to a firm conclusion. But I may be able to point to useful lines of enquiry.

For each pregnancy and birth I will look for any maternal disease, or potentially substandard obstetric care, that might have contributed to the babies’ later deaths or collapses. If further information comes to light, I will update.

I will also consider whether it had been appropriate at the time for each mother to have delivered in The Countess of Chester, a level 2 unit, and if not, whether opportunities were missed for transfer to a level 3 unit.

Finally I will consider whether it would hypothetically have been appropriate to deliver the mother in a level 1 unit, the level to which Chester was downgraded in July 2016. This may be relevant to the fall in the baby deaths at Chester at that time.

Tomorrow I will explain why this task may be relevant, and why I believe it has not already been done either by the prosecution or defence. I will also summarise the maternal information the Shoo Lee panel found in the baby records (click here).

Jim Thornton

Edited, 5 June, to clarify that Letby was “refused” rather than “lost” two appeals. Edited, 9 June, to clarify that air cannot be injected into a pulmonary vein. It may “accidentally enter” a pulmonary vein.

1. Footnote added 3 October 2025.
   People have told me that Letby was convicted of injecting air into an already installed intravenous line, or an intravenous long line, rather than cannulating a peripheral vein herself, and asked whether either possibility would invalidate the Shoo Lee panel’s hypothesis.
   
   It is correct that the prosecution alleged that she had injected air into a pre-existing line. It would be difficult to freshly cannulate a newborn baby’s peripheral vein without being noticed.
   
   However, air into peripheral veins or long lines are the same thing in this context. A long line passes up the peripheral veins, so the air would enter the bloodstream nearer the heart. But it would still arrive at the right side of the heart and need to pass through the lung arteries and into the lung capillaries, where it would be trapped, before it could return to the the left side of the heart to be pumped out into the systemic ciculation and appear in the skin. ↩︎