Researchers compare the ability of different fetal growth charts in predicting gestational age in a Chinese population
BEIJING, Jan. 4, 2023 /PRNewswire/ — Ultrasound imaging has emerged as a powerful tool for the safe and non-invasive visualization of a fetus. It enables the timely diagnosis of fetal abnormalities. Moreover, fetal measurements obtained using ultrasound-guided fetal biometry can be used to determine the gestational age and health of the baby. Reference fetal growth charts for head circumference (HC), biparietal diameter (BPD), abdominal circumference (AC), and femur length (FL), guide clinicians in assessing the gestational age of the fetus.
Several practitioners, however, rely on reference charts provided with the ultrasound machine. Commonly used standards, including the longstanding Hadlock references, are based on evidence drawn from the western population. Thus, their application in demographically diverse populations can be discrepant. This can have a profound impact on prenatal healthcare in Asian nations, which contribute significantly to the global population.
To this end, Professor Shengli Li and his team compared the ability of the Hadlock reference and other fetal growth charts in predicting newborn(s) small for gestational age (SGA), in a Chinese population. Explaining the rationale behind their work, published in the Chinese Medical Journal, Professor Li says, “Evidence has shown that fetal growth is largely influenced by ethnicity or nationality. Therefore, it would be risky if a reference or standard was directly taken into clinical practice without strict evaluation.”
The researchers retrospectively analyzed data from 169,980 ultrasound scans conducted across the second and third trimesters of 41,032 live-birth singleton pregnancies in Shenzhen city. Next, they generated a Shenzhen fetal growth chart using statistical models, for HC, BPD, AC and FL measurements, following which they compared the Shenzhen chart with other published charts. The number of fetuses with biometric measurements below the 3rd centile of the charts (i.e., fetuses that were SGA) was calculated and compared as a measure of potential bias across different growth charts.
Their findings revealed that a notable proportion of fetuses were misclassified as having small heads (8.9%) and short femurs (6.6%) while using the Hadlock references during late gestation. In contrast, the INTERGROWTH-21st standards performed better, while providing a closer estimate to the expected value, particularly for fat-free biometry (HC and FL).
A misdiagnosis of fetal smallness can trigger anxiety in the parents-to-be and lead them to opt for unnecessary and potentially invasive investigations. Reference charts based on the local population may, therefore, be beneficial for a more accurate fetal growth estimate.
In conclusion, Prof. Li states, “When applying published growth charts, utmost care should be taken to avoid inaccuracy due to the discrepancy of measurement methods.”
Title of original paper: Which fetal growth charts should be used? A retrospective
observational study in China
Journal: Chinese Medical Journal
SOURCE Chinese Medical Journal