Thompson H O, Casaceli C, Woods J R
Department of Obstetrics and Gynecology, University of Rochester, School of Medicine and Dentistry, Strong Memorial Hospital, NY 14642.
Am J Obstet Gynecol. 1990 Sep;163(3):986-95. doi: 10.1016/0002-9378(90)91110-x.
Estimated fetal weights from 1684 cases with singleton, live infants born within 7 days of an ultrasonographic examinations were compared with their birth weights, which ranged from 520 to 5920 gm. Estimated weight calculated from Shepard's equation produced a linear relationship of birth weight against estimated weight with an intercept and slope of 209.5 gm and 0.929. Overall, 75% of the estimated weights were within 15% of the actual weight. A separate regression model that used the same variables from Shepard's equation failed to improve the comparison between estimated and actual weights. All cases were reevaluated with multiple regression modeling. Various examination-to-birth intervals were analyzed; intervals less than or equal to 3 days appeared optimal. The best equation increased the percent of cases that were within 15% of the actual birth weight to 80%. The plot of birth weight against estimated weight had an intercept and slope of 33.1 gm and 0.994. Unlike Shepard's equation, the best equation was not statistically different from the ideal one-to-one relationship between estimated and actual weight. When the new equation was applied to an additional 339 new cases, equally accurate results were obtained. Customizing a laboratory's ultrasonographic weight estimation equations may be necessary to obtain the best estimate of fetal weight.
对1684例单胎、活产且在超声检查后7天内出生的婴儿的估计胎儿体重与其出生体重进行了比较，出生体重范围为520至5920克。根据谢泼德方程计算的估计体重得出出生体重与估计体重的线性关系，截距和斜率分别为209.5克和0.929。总体而言，75%的估计体重在实际体重的15%以内。一个使用与谢泼德方程相同变量的单独回归模型未能改善估计体重与实际体重之间的比较。所有病例均用多元回归模型重新评估。分析了不同的检查至出生间隔；小于或等于3天的间隔似乎最为理想。最佳方程使估计体重在实际出生体重的15%以内的病例百分比提高到了80%。出生体重与估计体重的图线截距和斜率分别为33.1克和0.994。与谢泼德方程不同，最佳方程与估计体重和实际体重之间理想的一对一关系在统计学上并无差异。当将新方程应用于另外339例新病例时，也获得了同样准确的结果。可能有必要定制实验室的超声体重估计方程，以获得胎儿体重的最佳估计值。
