Leung T Y, Sahota D S, Chan L W, Law L W, Fung T Y, Leung T N, Lau T K
Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Hong Kong, China SAR.
Ultrasound Obstet Gynecol. 2008 Jan;31(1):10-4. doi: 10.1002/uog.5206.
To determine whether the first trimester crown-rump length (CRL), maternal serum levels of pregnancy-associated plasma protein A (PAPP-A) and free beta-human chorionic gonadotropin (fbeta-hCG) are independent predictors of birth weight.
This was an observational study over 1.5 years in Chinese patients who underwent first-trimester combined screening for Down syndrome in a University fetal medicine unit. After excluding cases with multiple pregnancies, congenital malformations and in-utero deaths, the relationship between fetal CRL (expressed as standardized Z-score (Z-CRL)), maternal PAPP-A and fbeta-hCG levels (expressed as log(10) of multiples of the median) and birth weight (Z-BW) were analyzed by Pearson's correlation test followed by multiple regression to check for their independency. The predictive power of the independent predictors for small-for-gestational age (SGA, defined as birth weight < 10(th) centile) was then assessed using receiver-operating characteristics (ROC) curves, and the likelihood ratios were derived.
A total of 2760 cases were included. Z-CRL, log(10) PAPP-A(MoM), and log(10) fbeta-hCG were positively correlated with Z-BW (P < 0.0001), but only Z-CRL and log(10) PAPP-A(MoM) were independent predictors (P < 0.0001). The areas under the ROC curves of PAPP-A(MoM) and Z-CRL were 0.608 and 0.593, respectively (P < 0.0001). Likelihood ratios increased with decreasing PAPP-A(MoM) and Z-CRL, but were around 1 when the markers were at or above the mean.
First-trimester CRL and PAPP-A are independent factors that influence final birth weight. The lower the PAPP-A and the smaller the CRL, the higher the risk of a fetus becoming SGA. However, their predictive powers are not sufficiently good for them to be used alone for SGA screening.
确定孕早期头臀长（CRL）、孕妇血清妊娠相关血浆蛋白A（PAPP-A）和游离β-人绒毛膜促性腺激素（fβ-hCG）水平是否为出生体重的独立预测指标。
这是一项在大学胎儿医学科对进行孕早期唐氏综合征联合筛查的中国患者进行的为期1.5年的观察性研究。排除多胎妊娠、先天性畸形和宫内死亡病例后，通过Pearson相关检验分析胎儿CRL（以标准化Z评分（Z-CRL）表示）、孕妇PAPP-A和fβ-hCG水平（以中位数倍数的log(10)表示）与出生体重（Z-BW）之间的关系，随后进行多元回归以检验它们的独立性。然后使用受试者工作特征（ROC）曲线评估独立预测指标对小于胎龄儿（SGA，定义为出生体重<第10百分位数）的预测能力，并得出似然比。
共纳入2760例病例。Z-CRL、log(10)PAPP-A（MoM）和log(10)fβ-hCG与Z-BW呈正相关（P<0.0001），但只有Z-CRL和log(10)PAPP-A（MoM）是独立预测指标（P<0.0001）。PAPP-A（MoM）和Z-CRL的ROC曲线下面积分别为0.608和0.593（P<0.0001）。似然比随着PAPP-A（MoM）和Z-CRL的降低而增加，但当标志物处于或高于平均值时，似然比约为1。
孕早期CRL和PAPP-A是影响最终出生体重的独立因素。PAPP-A越低且CRL越小，胎儿成为SGA的风险越高。然而，它们的预测能力不够好，不足以单独用于SGA筛查。
