Intrauterine Growth Charts Used in Prenatal Diagnosis Centres: Repeated, National Cross‐Sectional Survey

The publication of international fetal growth charts by the Intergrowth-21st project (IG) and the World Health Organization (WHO) in 2017 initiated an ongoing debate about the criteria for selecting charts and the benefits of using charts based on low-risk pregnancies (prescriptive charts). These publications were followed by studies comparing these charts both with one another and with those used in clinical practice. These studies found that the proportions of fetuses with growth parameters under the 10th percentile, the commonly used threshold for fetal growth restriction (FGR) screening, differ across charts [1]. This research also showed heterogeneity in the choice of chart between and within countries, potentially leading to inconsistent identification and management of FGR [2]. In 2022, the two main French obstetric societies issued nonbinding guidelines to harmonise practices by adopting international prescriptive charts. However, their recommendations were discordant: the French College of Obstetricians and Gynecologists (CNGOF) recommended the WHO charts [3] while the French College of Fetal Sonography (CFEF) recommended the IG charts [4]. Previously, national intrauterine references produced by the CFEF using routine ultrasound measures had been recommended for biometric measures only. This study aimed to assess the impact of these guidelines on the choice of chart in French referral centres for prenatal diagnosis (Centre Pluridisciplinaire de Diagnostic PréNatal, CPDPN), where all practitioners refer pregnant women with suspected FGR for further multidisciplinary evaluation and follow-up. Data were collected from coordinators of all French CPDPN centres, which exist in 47 maternity units, in 2017 (pre-guidelines) and in 2023 (post-guidelines) via online questionnaires or telephone interviews. The questionnaires included the same questions on intrauterine charts used for screening (during systematic ultrasounds) and for diagnosis (to confirm pathological growth). The 2023 questionnaire included an additional multiple-choice question on the reasons for selecting the chart. Response rates were 100% (47 centres) and 95.7% (45 centres) in 2017 and 2023, respectively. In 2017, there were eight different charts used for screening, with 70.2% of CPDPN centres using the national CFEF chart, while IG charts were used in one centre and WHO charts in none (Table 1). In 2023, three different charts were used for screening, with WHO being the most common (71.1%), followed by IG (24.4%) and CFEF (4.4%). Results were similar for the charts used for diagnosis. A majority of centres based their choice on recommendations by professional societies: CNGOF (57.8%), their perinatal network (mandated regional structures that coordinate perinatal care between maternity units, 37.8%), CFEF (15.6%). These results confirm heterogeneity in the choice of charts in French CPDPN centres before the 2022 guidelines by the two principal French obstetric societies, and reveal a complete change in the charts following their publication, demonstrating how professional society recommendations can rapidly transform clinical practice. As CPDPN centres serve as referral centres for all French maternity units (≈450 in 2023), their choice of chart directs local sonographers regarding FGR screening and diagnosis, and likely gives a good overview of practices in the country in both periods. While most centres now use the WHO charts, one-quarter of centres opted for the IG charts. These charts have been shown to yield discordant screening results in France [1, 2], underscoring the need for performance evaluation to ensure consistent FGR detection and management nationally. To our knowledge, France and Chile, which recommended the WHO charts [5], are the only high-income countries to adopt these prescriptive charts. Future evaluations of outcomes in these countries would therefore provide a unique opportunity to inform the international debate about their utility. This further research should consider the broader diagnostic framework determining FGR management (e.g., screening thresholds, Doppler criteria and fetal heart rate monitoring), practitioner satisfaction and implementation challenges. S.M. and A.H. had full access to all of the data in the study and took responsibility for the integrity of the data and the accuracy of the data analyses. Study concept and design: A.H., A.P. Data acquisition: S.M., A.P. Data management and statistical analysis: S.M., A.H. Data interpretation: S.M., A.P., G.G., I.M., J.Z., A.H. Drafting of the manuscript: S.M., J.Z., A.H. Critical revision of the manuscript for important intellectual content and approval of the final version of the manuscript: S.M., A.P., G.G., I.M., J.Z., A.H. Open access publication funding provided by COUPERIN CY26. The authors have nothing to report. The authors have nothing to report. The authors declare no conflicts of interest. The data that support the findings of this study are available from CPDPN centres. Restrictions apply to the availability of these data, which were used under license for this study. Data are available from the author(s) with the permission of CPDPN centres.