Current fetal growth charts employed across England’s National Health Service (NHS) to monitor prenatal development may be misclassifying significant numbers of babies as either too small or too large. This discrepancy, revealed by a comprehensive study analyzing over 3.2 million births, highlights profound implications for perinatal care, including missed detection of growth restrictions associated with stillbirth and unnecessary medical interventions.
Fetal growth restriction, characterized by slower-than-expected intrauterine growth, is a critical predictor of adverse pregnancy outcomes. Detecting this condition prenatally is essential to improve neonatal safety and reduce avoidable perinatal deaths. However, the standard ‘one-size-fits-all’ growth charts currently implemented across NHS hospitals lack adjustment for maternal factors influencing fetal growth, such as maternal weight, ethnicity, and other physiological characteristics.
The study led by researchers at the Perinatal Institute in Birmingham compared seven widely used fetal growth standards, including Hadlock, Intergrowth-21st, World Health Organisation (WHO), Fetal Medicine Foundation (FMF), and the customised GROW charts. Unlike the universal charts, which use fixed references derived mostly from international populations, GROW employs a customizable algorithm, adapting fetal growth expectations based on individual maternal parameters.
Results underscored stark variability: rates of babies classified as small for gestational age (below the 10th centile) at term fluctuated considerably from 4.8% using Intergrowth charts to 17.2% with WHO and FMF charts, while GROW charts reported an intermediate rate of 12.3%. Moreover, unadjusted charts revealed inconsistent identification rates across different NHS regions reflecting local demographic differences, a variability not seen in customised assessments.
Importantly, the researchers utilized birthweight data for the analysis, acknowledging that ultrasound-estimated fetal weights might offer different insights but noting that birthweight metrics allowed inclusion of the entire cohort regardless of prenatal scan availability. The observational nature of the study provides strong epidemiological evidence but calls for further prospective validation.
These findings advocate urgent NHS-wide standardisation towards customised fetal growth assessment tools to enhance detection accuracy, improve clinical decision-making, and reduce avoidable fetal mortality. The study also calls for establishing real-time national oversight mechanisms to monitor chart performance, ensuring consistent quality and safety in maternity care.
The misapplication of non-personalised growth charts risks both false reassurance and overdiagnosis, potentially compromising maternal and fetal outcomes. This large-scale population study amplifies the pressing need for tailored clinical protocols that harmonize with diverse patient populations across the NHS.
As the NHS seeks to reduce perinatal mortality and improve antenatal care safety, adopting customised growth models may represent a critical evolution in fetal surveillance, aligning care with individual biological variance and scientific precision.
Subject of Research: People
Article Title: Designation of small for gestational age according to seven fetal growth charts in England’s National Health Service: population based cohort study of 3.2 million births
News Publication Date: 8-Jul-2026
Web References: http://dx.doi.org/10.1136/bmj-2026-433307
Keywords: Fetal growth charts, customized growth standards, fetal growth restriction, stillbirth risk, NHS maternity care, perinatal mortality, epidemiology
Tags: comparison of fetal growth standardscustomized versus universal growth chartsearly detection of growth abnormalitiesfetal growth restriction detectionimpact of maternal factors on fetal developmentimplications of fetal growth misclassificationmaternal ethnicity and weight influenceneonatal risk assessmentNHS fetal monitoring practicesperinatal care improvementspersonalized fetal growth chartspreventing stillbirth through accurate growth assessment
