The issue of fetal growth measurement and its impact on stillbirth prevention is a critical one, and a recent study highlights the flaws in the current system. The research, led by Jason Gardosi and published in the BMJ, reveals a stark disparity in the identification of small for gestational age (SGA) babies across England. This discrepancy is not due to negligence but rather the use of different fetal growth charts in various hospitals. The study examined data from 3.2 million births, revealing a wide variation in the proportion of babies identified as SGA, ranging from 5.5% to 18.7% depending on the chart used.
The core problem lies in the one-size-fits-all nature of some growth charts, which fail to account for maternal characteristics. For instance, the Hadlock, Intergrowth-21st, World Health Organisation standard, and Fetal Medicine Foundation charts do not adjust for factors like maternal height, weight, parity, and ethnic origin. This means a baby who is constitutionally small due to their mother's profile might be flagged as at risk, leading to unnecessary monitoring, while a baby who is pathologically small for their mother's profile might be missed entirely. The customized GROW chart, produced by the Perinatal Institute, is an exception, as it considers these maternal factors.
The consequences of these inconsistencies are severe. A baby flagged as dangerously small in one hospital might not be identified as such in a neighboring hospital using a different chart. This postcode lottery-like situation can have dire outcomes, including stillbirth. The study emphasizes the need for standardization in fetal growth risk assessment, management, and audit, as recommended by previous inquiries.
Regulators have taken some action, instructing NHS Trusts to stop using the INTERGROW EFW charts by March 2026. However, this move falls short of a comprehensive solution. The BMJ authors advocate for a coordinated national program with real-time oversight of quality and safety in maternity care. They argue that the evidence is already available, and what is lacking is a single body to mandate the use of a specific chart, fund training, and hold hospitals accountable.
The current system's flaws are not new, and previous inquiries have called for standardized protocols and an independent study of growth chart accuracy. The question remains: why has a single mandated standard not been implemented? Until a comprehensive solution is in place, the fate of babies in different hospitals will continue to depend on the chart used, rather than the baby's actual risk factors.
