Harris Birthright Research Centre for Fetal Medicine, King's College Hospital, London, UK.
Ultrasound Obstet Gynecol. 2015 Sep;46(3):332-40. doi: 10.1002/uog.14855. Epub 2015 Aug 6.
To investigate the potential value of uterine artery (UtA) pulsatility index (PI) and mean arterial pressure (MAP) at 19-24 weeks' gestation, in combination with maternal characteristics and medical history and fetal biometry in the prediction of delivery of small-for-gestational-age (SGA) neonates in the absence of pre-eclampsia (PE) and to examine the potential value of such assessment in deciding whether the third-trimester scan should be performed at 32 and/or 36 weeks' gestation.
This was a screening study in 63 975 singleton pregnancies, including 3702 (5.8%) that delivered SGA neonates with birth weight < 5(th) percentile (SGA < 5(th) ) in the absence of PE. Multivariable logistic regression analysis was used to determine if screening by a combination of maternal factors, fetal head circumference (HC), abdominal circumference (AC), femur length (FL), UtA-PI and MAP had significant contribution in predicting SGA neonates. A model was developed to select gestational age for the third-trimester assessment, at 32 and/or 36 weeks, based on the results of screening at 19-24 weeks.
The detection rates (DRs) of combined screening by maternal factors, fetal biometry and UtA-PI at 19-24 weeks were 90%, 68% and 44% for SGA < 5(th) delivering < 32, 32-36 and ≥ 37 weeks' gestation, respectively, at a false-positive rate (FPR) of 10%. The performance of screening was not improved by the addition of MAP. The DR of SGA < 5(th) delivering at 32-36 weeks improved from 68% to 90% with screening at 32 rather than at 19-24 weeks. Similarly, the DR of SGA < 5(th) delivering ≥ 37 weeks improved from 44% with screening at 19-24 weeks to 59% and 76% when screening at 32 and 36 weeks, respectively. In a hypothetical model, it was estimated that if the desired objective of prenatal screening is to predict about 80% of the cases of SGA < 5(th) , it would be necessary to select 17% of the population at the 19-24-week assessment to be reassessed at 32 weeks and 38% to be reassessed at 36 weeks; 62% would not require a third-trimester scan.
Prenatal prediction of a high proportion of SGA neonates necessitates the undertaking of screening in the third trimester of pregnancy in addition to assessment in the second trimester, and the timing of such screening, at 32 and/or 36 weeks, should be contingent on the results of the assessment at 19-24 weeks.
研究孕 19-24 周时子宫动脉（UtA）搏动指数（PI）和平均动脉压（MAP）与母亲特征、病史和胎儿生物测量相结合，在预测无子痫前期（PE）的胎儿生长受限（SGA）新生儿中的潜在价值，并探讨这种评估方法在决定是否应在 32 周和/或 36 周行孕晚期超声检查中的潜在价值。
这是一项对 63975 例单胎妊娠的筛查研究，其中 3702 例（5.8%）在无 PE 的情况下分娩出生体重<第 5 百分位数（SGA < 5th）的 SGA 新生儿。采用多变量逻辑回归分析来确定是否通过结合母亲因素、头围（HC）、腹围（AC）、股骨长（FL）、UtA-PI 和 MAP 进行筛查，可以显著预测 SGA 新生儿。根据 19-24 周的筛查结果，建立了一种选择 32 周和/或 36 周行孕晚期评估的模型。
在假阳性率（FPR）为 10%的情况下，19-24 周时母亲因素、胎儿生物测量和 UtA-PI 联合筛查的检测率（DR）分别为 90%、68%和 44%，用于预测分娩孕周<32 周、32-36 周和≥37 周的 SGA<5th。MAP 的加入并不能提高筛查的效果。与 19-24 周筛查相比，仅在 32 周筛查时，SGA<5th 分娩于 32-36 周的 DR 从 68%提高到 90%。同样，SGA<5th 分娩于≥37 周的 DR 从 19-24 周筛查时的 44%提高到 32 周和 36 周筛查时的 59%和 76%。在一个假设模型中，如果产前筛查的目的是预测约 80%的 SGA<5th 病例，那么在 19-24 周评估时需要选择 17%的人群在 32 周时重新评估，38%的人群在 36 周时重新评估；62%的人不需要进行第三次妊娠扫描。
为了预测大量 SGA 新生儿，需要在孕晚期进行筛查，除了在孕中期进行评估外，还需要在孕晚期进行筛查，筛查时间（32 周和/或 36 周）应取决于孕 19-24 周的评估结果。
