Nuffield Department of Women's and Reproductive Health, University of Oxford, Oxford, UK.
Centre for Statistics in Medicine, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, UK.
BJOG. 2024 Dec;131(13):1862-1873. doi: 10.1111/1471-0528.17922. Epub 2024 Aug 8.
Accurate assessment of gestational age (GA) is important at both individual and population levels. The most accurate way to estimate GA in women who book late in pregnancy is unknown. The aim of this study was to externally validate the accuracy of equations for GA estimation in late pregnancy and to identify the best equation for estimating GA in women who do not receive an ultrasound scan until the second or third trimester.
This was a prospective, observational cross-sectional study.
57 prenatal care centres, France.
Women with a singleton pregnancy and a previous 11-14-week dating scan that gave the observed GA were recruited over an 8-week period. They underwent a standardised ultrasound examination at one time point during the pregnancy (15-43 weeks), measuring 12 foetal biometric parameters that have previously been identified as useful for GA estimation.
A total of 189 equations that estimate GA based on foetal biometry were examined and compared with GA estimation based on foetal CRL. Comparisons between the observed GA and the estimated GA were made using R, calibration slope and intercept. RMSE, mean difference and 95% range of error were also calculated.
A total of 2741 pregnant women were examined. After exclusions, 2339 participants were included. In the 20 best performing equations, the intercept ranged from -0.22 to 0.30, the calibration slope from 0.96 to 1.03 and the RSME from 0.67 to 0.87. Overall, multiparameter models outperformed single-parameter models. Both the 95% range of error and mean difference increased with gestation. Commonly used models based on measurement of the head circumference alone were not amongst the best performing models and were associated with higher 95% error and mean difference.
We provide strong evidence that GA-specific equations based on multiparameter models should be used to estimate GA in late pregnancy. However, as all methods of GA assessment in late pregnancy are associated with large prediction intervals, efforts to improve access to early antenatal ultrasound must remain a priority.
The proposal for this study and the corresponding methodological review was registered on PROSPERO international register of systematic reviews (registration number: CRD4201913776).
准确评估孕周（GA）在个体和人群层面都非常重要。对于妊娠晚期才建档的孕妇，最准确的 GA 估计方法尚不清楚。本研究旨在对外验证晚期妊娠 GA 估计方程的准确性，并确定适用于第二或第三孕期才接受超声检查的孕妇 GA 估计的最佳方程。
这是一项前瞻性、观察性的横断面研究。
法国 57 个产前护理中心。
招募了在 8 周内接受过 11-14 周的孕早期超声检查且结果与观察到的 GA 相符的单胎妊娠孕妇。她们在妊娠期间的一个时间点（15-43 周）接受了标准化的超声检查，测量了 12 项先前被确定为有助于 GA 估计的胎儿生物计量参数。
共检查了 189 个基于胎儿生物计量的 GA 估计方程，并与基于胎儿 CRL 的 GA 估计进行了比较。通过 R 进行比较，比较了观察到的 GA 与估计的 GA，校准斜率和截距。还计算了 RMSE、平均差异和 95%误差范围。
共检查了 2741 名孕妇，排除后共纳入 2339 名参与者。在 20 个表现最佳的方程中，截距范围为-0.22 至 0.30，校准斜率范围为 0.96 至 1.03，RMSE 范围为 0.67 至 0.87。总体而言，多参数模型优于单参数模型。95%误差范围和平均差异均随胎龄增加而增加。通常使用的基于头围测量的单一参数模型不是表现最佳的模型之一，与较高的 95%误差和平均差异相关。
我们提供了强有力的证据表明，应使用基于多参数模型的特定 GA 方程来估计晚期妊娠的 GA。然而，由于所有晚期妊娠 GA 评估方法均存在较大的预测区间，因此仍需努力改善早期产前超声检查的可及性。
该研究的方案和相应的方法学审查已在 PROSPERO 国际系统评价注册库中进行了注册（注册号：CRD4201913776）。
