Fetal Medicine Research Institute, King's College Hospital, London, United Kingdom.
Institute of Health Research, University of Exeter, Exeter, United Kingdom.
Am J Obstet Gynecol. 2023 Jul;229(1):57.e1-57.e14. doi: 10.1016/j.ajog.2022.12.318. Epub 2022 Dec 31.
Antenatal identification of pregnancies at high risk of delivering small for gestational age neonates may improve the management of the condition and reduce the associated adverse perinatal outcomes. In a series of publications, we have developed a new competing-risks model for small for gestational age prediction, and we demonstrated that the new approach has a superior performance to that of the traditional methods. The next step in shaping the appropriate management of small for gestational age is the timely assessment of these high-risk pregnancies according to an antenatal stratification plan.
This study aimed to demonstrate the stratification of pregnancy care based on individual patient risk derived from the application of the competing-risks model for small for gestational age that combines maternal factors with sonographic estimated fetal weight and uterine artery pulsatility index at midgestation.
This was a prospective observational study of 96,678 singleton pregnancies undergoing routine ultrasound examination at 19 to 24 weeks of gestation, which included recording of estimated fetal weight and measurement of uterine artery pulsatility index. The competing-risks model for small for gestational age was used to create a patient-specific stratification curve capable to define a specific timing for a repeated ultrasound examination after 24 weeks. We examined different stratification plans with the intention of detecting approximately 80%, 85%, 90%, and 95% of small for gestational age neonates with birthweight <3rd and <10th percentiles at any gestational age at delivery until 36 weeks; all pregnancies would be offered a routine ultrasound examination at 36 weeks.
The stratification of pregnancy care for small for gestational age can be based on a patient-specific stratification curve. Factors from maternal history, low estimated fetal weight, and increased uterine artery pulsatility index shift the personalized risk curve toward higher risks. The degree of shifting defines the timing for assessment for each pregnancy. If the objective of our antenatal plan was to detect 80%, 85%, 90%, and 95% of small for gestational age neonates at any gestational age at delivery until 36 weeks, the median (range) proportions (percentages) of population examined per week would be 3.15 (1.9-3.7), 3.85 (2.7-4.5), 4.75 (4.0-5.4), and 6.45 (3.7-8.0) for small for gestational age <3rd percentile and 3.8 (2.5-4.6), 4.6 (3.6-5.4), 5.7 (3.8-6.4), and 7.35 (3.3-9.8) for small for gestational age <10th percentile, respectively.
The competing-risks model provides an effective personalized continuous stratification of pregnancy care for small for gestational age which is based on individual characteristics and biophysical marker levels recorded at the midgestation scan.
对有发生小于胎龄儿风险的孕妇进行产前识别，可能改善对这种情况的管理并减少相关的围产期不良结局。在一系列出版物中，我们开发了一种新的预测小于胎龄儿的竞争风险模型，并且已经证明这种新方法比传统方法具有更好的性能。为了对小于胎龄儿进行适当的管理，下一步是根据产前分层计划及时评估这些高危妊娠。
本研究旨在根据结合了母亲因素、中孕期超声估计胎儿体重和子宫动脉搏动指数的竞争风险模型，为基于个体患者风险的妊娠护理分层，该模型可用于预测小于胎龄儿。
这是一项对 96678 例接受 19 至 24 周常规超声检查的单胎妊娠进行的前瞻性观察性研究，包括记录估计的胎儿体重和测量子宫动脉搏动指数。使用竞争风险模型对小于胎龄儿进行个体化分层，创建一个能够在 24 周后为重复超声检查定义特定时间的个体化分层曲线。我们研究了不同的分层方案，目的是在分娩前任何孕周至 36 周时，以 80%、85%、90%和 95%的检测率检测到所有小于胎龄儿，出生体重＜第 3 百分位和＜第 10 百分位；所有妊娠将在 36 周时接受常规超声检查。
可根据患者的个体化分层曲线对小于胎龄儿的妊娠护理进行分层。来自母亲病史、低估计胎儿体重和增加的子宫动脉搏动指数的因素会使个体化风险曲线向更高的风险转移。这种转移的程度定义了对每个妊娠的评估时间。如果我们的产前计划的目标是在分娩前任何孕周至 36 周时，以 80%、85%、90%和 95%的检测率检测到所有小于胎龄儿，则每周接受检查的人群中位数（范围）比例（%）分别为 3.15（1.9-3.7）、3.85（2.7-4.5）、4.75（4.0-5.4）和 6.45（3.7-8.0），对于出生体重＜第 3 百分位；3.8（2.5-4.6）、4.6（3.6-5.4）、5.7（3.8-6.4）和 7.35（3.3-9.8），对于出生体重＜第 10 百分位。
竞争风险模型为基于个体特征和中孕期超声检查记录的生物物理标志物水平的小于胎龄儿妊娠护理提供了有效的个体化连续分层。
