中文摘要：

目的：生长发育评价标准的最佳形式是年龄别百分位数，然而，目前我国缺乏胎儿的孕周别体格发育指标百分位数评价标准，影响了胎儿宫内生长发育水平的准确评价，本研究拟建立陕西省正常单胎妊娠孕妇胎儿体格发育指标百分位数参考标准。方法：以陕西省西安、汉中、延安5所大型综合医院超声科或妇产科超声室为数据采集点，选择2010-01-01到2010—12-31间进行常规孕期检查的正常单胎妊娠胎儿的超声测量数据，随机抽取一次测量结果，共收集到6832个单胎正常妊娠胎儿的超声测量数据。采用三次样条法对陕西省孕16—41周正常单胎妊娠胎儿的双顶径、腹围、股骨长百分位数进行拟合。结果：三次样条拟合胎儿的双顶径、腹围、股骨长百分位数，各百分位数的决定系数均在0．95以上，均方差均在各指标重复测量的容许误差内，拟合结果满意。计算出了胎儿的孕周别双顶径、腹围、股骨长的P3、PIO、P25、P50、P75、P90、P97百分位数。结论：三次样条兼顾了曲线拟合中的拟合优度和光滑度，能更好的实现曲线拟合的目的。所建立的孕周别胎儿体格发育指标百分位数符合胎儿宫内生长发育规律，为胎儿宫内生长发育的准确评价提供了科学、准确的评价工具，可用于产科临床和研究工作中。

英文摘要：

Objective ： The best assessment standard for growth and development is age related centile. Presently, there is not a centile reference standard of fetal physique index in China, this may influence the accuracy of fetal growth and development assessment. So we want to construct centile reference of fetal biometry for singleton pregnant women in Shaanxi, China. Methods： Department oful- trosonic or ultrasonic division of department of obstetrics and gynaecology of five large hospitals in Xi＇an, Hanzhong and Yanan were sel- ected as data collection spot. 6,832 singleton pregnant women who have a regular pregnant examination between 2010-01-01 to 2010-12-31 in the selected hospitals were selected. One set of fetal ultrasonography measurement data between the 16th to 41th gestational weeks was randomly selected from each pregnant woman, and biparietal diameter, abdominal circumference and femur length were recorded. Centiles ofbiparietal diameter, abdominal circumference and femur length of fetus pregnant between 16 to 41 weeks were directly calculated and then fitted by cubic smoothing spline. Results： All the coefficient of determination （R2） of each centile for biparietal diameter, abdominal circumference and femur length fitted by cubic smoothing spline were all above 0.95. And all the mean square of error of each centile for biparietal diameter, abdominal circumference and femur length did not exceed its re-measurement error limitation. Centiles for gestational week specified P3, P10, P25, PS0, P75, P90, P97 for biparietal diameter, abdominal circumference and femur length were calculated and presented as tables. Conclusion： Both goodness of fitting and smoothness are satisfactory for curves fitting by the method of cubic smoothing spline. This method can realize curve fitting aim better. Reference centiles for fetal physique indexes constructed by cubic smoothing spline were accordant with fetal growth and development rule, they were accurate tool for fetal