A quarter of a century of stillbirth prevention strategy hinges on a single clinical judgement: is this baby measuring smaller than it should be. Get that judgement wrong, and a baby at real risk of growth restriction slips through unnoticed until it is too late. New research published this month suggests that judgement is being made inconsistently across England, not because clinicians are careless, but because the tools they are handed differ from hospital to hospital
The study, led by Jason Gardosi and published in the BMJ, examined data on 3.2 million births between 2015 and 2025, drawn from 38 of England's integrated care boards. It found that the proportion of babies identified as small for gestational age varied widely depending on which fetal growth chart was used, ranging from 5.5% to 18.7%. That is not a marginal statistical quirk. It means a baby flagged as dangerously small in one trust might pass through an identical pregnancy in a neighbouring trust and never be flagged at all.
The reason lies in the charts themselves. Six of the charts in use, including Hadlock, Intergrowth-21st, the World Health Organisation standard and the Fetal Medicine Foundation chart, are one-size-fits-all measures that cannot be adjusted for maternal characteristics. The seventh, the customised GROW chart produced by the Perinatal Institute, factors in maternal height, weight, parity and ethnic origin before deciding whether a baby's growth is a cause for concern. A baby who is constitutionally small because of who its mother is will be flagged as at risk on a generic chart and monitored unnecessarily. A baby who is pathologically small for its own mother's profile may be waved through as normal. Both errors carry consequences, but the second is the one that ends in stillbirth.
Regulators have already begun to respond, if only partially. NHS Trusts using INTERGROWTH EFW charts have been instructed to stop by 31 March 2026, following a safety alert from NHS England. But the instruction stops short of a fix. NHS England has not undertaken a new national review of the evidence comparing available growth charts, and the alert does not recommend a specific alternative. Trusts have been told to abandon one flawed method without being told which of the remaining six, or the customised GROW protocol, they should adopt in its place. That leaves the same postcode lottery in place under a different label.
This is not the first time fetal growth measurement has surfaced as a named failure. The independent review into maternity services at Nottingham University Hospitals concluded that there must be standardisation of fetal growth risk assessment, management and audit across RCOG, SBLCB and NICE guidance, with clear recommendations on which pathways and charts should be used. The National Maternity and Neonatal Investigation's final report went further, calling for an independent study of the accuracy of different growth charts and their ability to reduce adverse outcomes. Two separate national inquiries have now landed on the same conclusion. Neither has yet produced a single mandated standard.
The BMJ authors are direct about what they think should happen next. They argue that individual trusts tend to encounter rare but catastrophic outcomes too late, shaped by local protocols and practice, and call for a co-ordinated national programme with real-time oversight of quality and safety in this area of maternity care.
What is missing is not evidence. The evidence has been assembled twice over, once by researchers and once by statutory inquiry. What is missing is a single body willing to name the chart, fund the training, and hold trusts to it. Until that happens, a baby's chance of being correctly identified as at risk will continue to depend less on their mother's pregnancy than on which hospital she happens to walk into.
