【作者】 王珂；

【导师】 刘保平；

【作者基本信息】 郑州大学 ， 影像医学与核医学， 2009， 硕士

【摘要】 背景与目的胎儿体重是分娩过程中相对固定不变的因素,是决定分娩难易的重要因素之一,因此产前准确预测胎儿体重至关重要,对分娩时机、方式的选择和处理具有指导意义,但准确估计胎儿体重又有一定难度。80年代早期以前,胎儿体重的估测主要依靠临床应用腹部触诊,测量孕妇宫底高度和腹围来估测,但是由于受到腹壁厚度、子宫张力、羊水量、胎位等多种因素的影响,临床测量方法虽然简便但误差较大不够准确。过去的30余年,超声的出现及使用的普及,可以更直接地观察到胎儿在宫内的情况,并为胎儿体重估测提供了新的更准确方法。利用超声测量胎儿各项生物指标,可观察胎儿宫内的生长发育情况,一方面辅助临床诊疗胎儿宫内生长发育迟缓（Intrauterine growth restriction,IUGR）,另一方面为巨大儿等异常情况选择安全的分娩方式提供极为重要的参考依据。早在上个世纪70年代国内外就已开始了这项研究。近年来随着超声技术的普及和应用,越来越多的生物指标被用来监测胎儿宫内生长发育,并为胎儿体重估测提供了新的更准确的方法。随着超声技术的不断进步,预测胎儿体重方面的应用不断在实践中逐步改进,从一开始的单纯双顶径（biparietal diameter,BPD）的测量,到股骨长度（femur length,FL）、腹围（abdomen circumference,AC）、肝脏的测量,到近年来小脑横径、脊柱长度、皮脂厚度等新的测量指标的发现,观察的生物学参数已从单项指标数到多项指标数。但在妊娠晚期,胎儿在宫腔内位置的变化和身体各器官生长的非同步性等原因均给超声的准确测量带来一定的困难及影响。不同指标预测的准确率也有很大的差异,临床上难以确定是那种方法最适合。直到目前为止,没有证据能证明哪一种能明显优于其他的超声测量方法。对于人类而言发现一种简便、有效又准确的测量方法非常重要,尤其是在缺少昂贵测量仪器支持的发展中国家。目前广为应用的彩色超声诊断仪多带有产科方面的软件,其中包括估测胎儿体重,只需将计算公式规定的各项超声测量值结果输入,即可迅速获得胎儿估计体重,方法极为简便。本研究利用二维超声显像技术对妊娠晚期胎儿双顶径、腹围和股骨长度进行测量,通过常用公式推导计算出预测的胎儿体重,并与胎儿出生体重（fetal birthweight,FBW）相对比。旨在通过测量几种不同的胎儿生物指标,前瞻性的对比多项指标与单项指标在预测准确性上是否有统计学差异;了解产前巨大儿的超声预测及相关因素,探讨腹围与巨大儿的相关性;腹围采用两种测量方法:一种是传统的测量方法,另一种是近年发现的新的简便的测量方法,同时对同一胎儿用两种方法进行腹围测量,分别估计胎儿体重,并与出生体重对比分析,比较二者之间有无明显差异,来寻求一种实际工作中可选择的既相对准确而又更方便、更清晰、更易于显示的超声预测胎儿体重的测量方法。本研究分以下两部分:第一部分超声预测胎儿体重不同方法的对比研究对象与方法1随机选取2007年1月至2008年6月在我院进行产前超声检查,并于检查后72小时内在我院分娩的单胎或双胎健康孕妇500例,排除妊娠并发症、合并症及产前超声检查胎儿有明显畸形者。年龄19～42岁,平均年龄（27.5±4.6）岁;孕周32～42周,平均（38.8±3.5）周。新生儿出生后30分钟内称重。2仪器使用GELogiq500,探头频率3.5MHz。新生儿体重测量仪为无锡市衡器厂生产的RTz一10A型婴儿秤。3孕妇取平卧位,常规产科超声检查排除胎儿畸形。于分娩前72小时内由同一熟练掌握超声测量技能的医师测量胎儿的双顶径（BPD,mm）、腹围（AC,mm）和股骨长度（FL,mm）。每项指标均重复测量3次取平均值。其中腹围的测量采用两种测量方法,第一种是传统的测量方法,取超声医学第三版所述之标准即切面包括肝脏,肝内见门静脉左支的脐部,显示的门静脉与胎腹两侧壁基本等距,脐静脉长度约为胎腹前后径的1/3,并且切面与脊柱垂直。测量时须包括胎儿皮肤,记为AC₁。第二种是新的简便的测量方法:取包含胃泡,肝脏并与脊柱垂直的最大腹围层面,无需显示脐静脉,并且此层面上不应出现心脏,肾脏,测量需包括胎儿皮肤,记为AC₂。均使用轨迹球沿胎儿腹部外缘直接描记取值。②双顶径及股骨长度均采用目前国内外通用的测量方法。估计胎儿体重计算方程式有以下几种（Y表示胎儿体重,单位:g）;单项指标数计算的方程式:①与双顶径相关:Y=51.43×BPD-1516.9②与股骨长度相关:Y=2616.26+82.419×FL③与腹围相关:Y=25.2×AC-1713.3（AC≥223mm）Y=29.6×AC-2918.6（AC＜223mm）Y=27.3×AC+20.3×FL-3814.6（怀疑IUGR）双项及多项指标数计算的方程式:④与双顶径、腹围相关:Log10Y=1.599+0.144×BPD+0.032×AC-0.111×BPD×AC/1000⑤与双顶径、股骨长度、腹围同相关:Log10Y=1.4787-0.003343×AC×FL+0.001837×BPD+0.0458×AC+0.158×FL4新生儿体重及各径线的测量:新生儿出生后30分钟内由同一医师在新生儿全身裸露的情况下用直尺测量新生儿的双顶径（双侧顶骨最外缘的距离）、股骨长（取股骨两远端间的距离）和腹围（围绕脐1周的距离）。5产前产后胎儿体重绝对误差值在250g及其以内记为符合预测,相差＞250g则记为不符合预测（绝对误差值=实际体重一预测体重）。6采用SPSS13.0统计学软件进行分析。所有定量数据用（?）±S表示,应用方差齐性检验、t检验、单因素及随机区组方差分析、x²检验及相关性分析。取P＜0.05作为差异有统计学意义的检验标准。结果1各径线超声测量及生后测量值对比差异无统计学意义（P＞0.05）。2单项指标中AC与新生儿出生体重的相关系数最高,与BPD、FL对比有统计学差异（P＜0.05）,而在AC二种测量方法之间无统计学差异,（P＞0.05）。多项指标与新生儿出生体重相关系数较高,但BPD+AC组与BPD+AC+FL之间无统计学差异（P＞0.05）。3单项指标AC组较BPD、FL组估计胎儿体重与新生儿体重符合率比较有统计学差异（P＜0.05）,AC符合率较高,但明显低于多项指标（P＜0.05）。双项指标组BPD+AC组与多项指标组BPD+AC+FL组符合率比较后者高于前者,有统计学差异（P＜0.05）。4将新生儿体重分为＜2500g、2500-3999g、≥4000g三组,三组间预测胎儿体重绝对误差有统计学差异（P＜0.05）,2500-3999g组误差较小。具体行组间两两比较,显示:2500-3999g组与另两组间均有统计学差异（P＜0.05）;而＜2500g与≥4000g两组间比较无统计学差异（P＞0.05）。5 BPD+AC₁组和BPD+AC₂组两种腹围测量方法所估计胎儿体重绝对误差值无统计学差异（P＞0.05）;BPD+AC₁+FL组和BPD+AC₂+FL组两种腹围方法所估计胎儿体重绝对误差值亦无统计学差异（P＞0.05）。6两种腹围测量方法预测胎儿体重的符合率比较:BPD+AC₁组和BPD+AC₂组两种腹围测量方法所估计胎儿体重符合率比例无统计学差异（P＞0.05）;BPD+AC₁+FL组和BPD+AC₂+FL组两种测量腹围方法所估计胎儿体重符合率比例亦无统计学差异（P＞0.05）。7多项指标预测不同性别胎儿的体重结果比较:500例胎儿中,男孩是266例,女孩是234例,男孩和女孩两组相比较,实际体重较估计体重男孩组平均偏大,而女孩组平均偏小;在绝对误差小于等于250g的比例上女孩组要高于男孩组,但二组间的差异没有统计学的意义（P＞0.05）。结论1单项指标中AC单独预测胎儿体重的准确性最好,与新生儿出生体重的直线相关系数最高,明显优于BPD和FL组。2使用BPD、FL及AC多个指标能更准确地估测胎儿体重。3两种测量腹围方法所估计的胎儿体重比较没有差别,可以安全地采用更简便的方法:测量标准二来测量胎儿腹围进行胎儿体重的估计。4相同测量经线值的男孩出生体重较女孩大,虽然没有统计学上差异,但如果在估测时将该影响因素考虑进来,或建立计算方程式时将性别因素加入可提高预测结果的准确性。5目前的预测方法受到测量与分娩时间间隔及新生儿出生体重大小的影响。测量后3～4天内出生的新生儿体重预测准确性较好,且对于正常体重范围内的新生儿预测准确性明显高于较大或较小出生体重的新生儿。第二部分超声胎儿腹围测量与巨大胎儿的关系对象与方法1随机选取2007年1月至2008年6月在我院进行产前超声检查,并于检查后72小时内在我院分娩的单胎或双胎健康孕妇436例。排除妊娠并发症、合并症,及产前超声检查胎儿有明显畸形者。年龄20～41岁,平均年龄（27.1±4.3）岁;孕周≥37周,平均（39.2±2.7）周。新生儿出生后30分钟内称重,其中巨大儿设为观察组,余为对照组。2使用仪器同第一部分。3新生儿出生体重≥4000g为巨大胎儿。4孕妇取平卧位,常规产科超声检查排除胎儿畸形。于分娩前72小时内由同一熟练掌握超声测量的医师测量胎儿的双顶径（BPD,mm）、腹围（AC,mm）和股骨长度（FL,mm）。各指标超声的测定标准同第一部分,其中腹围测量方法采用传统测量法,即超声医学第三版所述之标准切面。胎儿体重计算方程式同第一部分中单项指标数计算的方程式。同时收集两组孕妇的年龄、身高、体重、胎龄等资料。5采用SPSS13.0统计学软件进行线性回归分析,定量资料采用t检验,计数资料组间比较用x²检验。敏感度和特异度有2×2表得出。取P＜0.05作为差异有统计学意义的检验标准。结果1本组经超声检测的436例新生儿中,体重达到或超过4 000 g的巨大胎儿86例,其中男婴62例,女婴24例,男女比为2.58:1。两组孕妇的年龄、腹围差异均无显著性（P＞0.05）。两组孕妇身高、宫高、分娩前体重及孕期体重增长幅度均有统计学差异（P＜0.05）。城市比例巨大儿组为87%,非巨大儿组为43%。2观察组延期妊娠（≥40周,＜42周）率高于对照组,具有统计学差异（x²=32.80,P＜0.05）,观察组过期妊娠（≥42周）例数与对照组比较差异无统计学意义（x²=2.708,P＞0.05）。3分娩方式观察组剖宫产率高于对照组,差异有统计学差异（P＜0.05）。4胎儿BPD、AC、FL与巨大胎儿体重存在直线相关关系,相关系数r值分别为0.59257、0.76179、0.60255。5当BPD≥95mm、AC≥350mm、FL≥75mm时,巨大儿发生率明显增多（P＜0.05）,AC≥350mm时其敏感度、阳性预测值、阴性预测值均为最高。当AC≥370mm时,期预测巨大儿特异度达97.1%。结论1巨大儿的发生与孕期过多的营养进补,运动减少等人为因素密切相关,而与孕妇的年龄层次关系不大。非糖尿病的孕妇肥胖者胎儿体重较易超重;受遗传因素的影响,父母身材高大肥胖者易发生巨大儿。2延期、过期妊娠是发生巨大儿的重要产科病理因素,临床上及时给予妊娠时限的医学干预,则可明显减少巨大儿的发生率。3 AC与预测巨大儿的一元相关系数明显高于BPD、FL。AC≥350mm时巨大儿发生率明显增多;AC≥370mm可作为预测胎儿大小的单一指标。4巨大儿并非为阴道分娩的禁忌症,应具体结合胎儿大小及产妇骨盆产道情况个体化选择分娩方式,部分可望在严密产程观察下顺利经阴道分娩。更多还原

【Abstract】 Background and purposeFetal weight is a relatively fixed factor during delivery, and is one of the important factors considering whether the delivery is easy or hard. So an accurate prenatal prediction of fetal weight is essential and very important for the selection of delivery time, mode and treatment, but an accurate estimation of fetal weight is difficult. Before the 1980’s, the estimation of fetal weight was mainly depended on the clinical application of abdominal palpation to decide height of uterine fundus and abdominal circumference of the mothers, but because of the impact of a variety of factors such as abdominal wall thickness, uterine tension, amniotic fluid volume, fetal position and so on, the clinical measurement method was simple but not accurate enough.Over the past 30 years, through the use of ultrasound, the fetus could be more directly observed in utero, and a new more accurate method for fetal weight estimation was provided. Using the supersonic survey to estimate each embryo biological indicator and observe the embryo growth situation in utero, on the one hand was auxiliary in the clinical diagnosing and treating intrauterine growth restriction （IUGR）, on the other hand provided the great important reference for selectiving secure delivery manner in fetal macrosomia. As early as in the 1970s, natives and foreigners had started this research. In recent years along with the supersonic technology’s popularization and the application, more and more biological indicators have been used for monitoring the embryo growth in utero, and providing a new more accurate method for the embryo body weight estimating. Along with the supersonic technology’s unceasing progress, the aspect of forecasting the embryo body weight application improves gradually in reality unceasingly, from the very beginning pure biparietal diameter（BPD） survey, to femur length（FL）, abdomen circumference（AC）, liver’s survey, to recent years new survey target discovery such as cerebellum transverse diameter, spinal column length, sebum thickness and so on, observation biology parameters have already changed from single item target number to many target numbers. But in the later period pregnancy, the embryo reasons that the position changes and bodily various organs grow non-synchronizedly in the palace cavity bring the supersonic correct measurement to a certain difficulty. Prediction accuracy rate of different indicators also has significant differences, so clinically it is difficult to determine which kind of method is most suitable. So far, there is no evidence to prove that which can be obviously superior to other ultrasonic measurement method. It is very important for humans to develop a simple, effective and accurate measurement, especially in developing countries with absent supportment of expensive measuring instruments. Currently widely used color ultrasound diagnostic apparatus always has obstetric software including the estimation of fetal weight. Providing the formula for calculating the value of the results in ultrasound measurement, you can quickly get an estimated fetal weight, extremely simple.In this study, we used two-dimensional ultrasound imaging technology on the third trimester of fetal to measure: the biparietal diameter, abdomen circumference and femur length, calculated the prediction of fetal weight through the commonly used formula and compared them with fetal birth weight（FBW）. We measured several different indicators of fetal biology and contrasted a number of forward-looking indicators to the individual indicator in the accuracy of prediction to decide whether there is statistical differences, and to learn prenatal ultrasound prediction of macrosomia and related factors to explore the relevance between abdominal circumference and macrosomia. Abdominal circumference was measured using two methods. One was the traditional measurement method, and the other was found in recent years, a new simple measurement method. At the same time, we used two methods of fetal abdominal circumference measurement to estimate fetal weight respectively, and compared them with birth weight to know whether there was significant difference between the two, in order to find a measurement method in the choice of both relatively accurate and more convenient, more precise and more easy to show the ultrasound prediction of fetal weight in clinical practice.This study is divided into two parts as below:The first part: the comparative study of different methods byUltrasound for fetal Weight predictionObjects and methods1 Healthy pregnant women with a single child or twins from January 2007 to June 2008 at our hospital were randomly selected for prenatal ultrasound examination and delivery in 72 hours after inspection at my department. Stand part of the study was excluded from pregnancy complications, as well as prenatal ultrasonography of obvious fetal malformations. A total of 500 cases were selected, aged at 19～42 years old, an average of （27.5±4.6） years, with 32～42 weeks gestational age, an average of （38.8±3.5） weeks. After birth the neonatals were weighted within 30 minutes.2 Instruments were GELogiq500, with probe frequency of 3.5MHz. The fetal birth weight was weighted by infant scales RTz—10A which was made in weighting apparatus factory in Wuxi city.3 Pregnant women were in supine position, taking conventional obstetric ultrasound examination to exclude fetal malformations. In 72 hours before delivery, the same physician who mastered the skills of ultrasound measurement estimated the fetal biparietal diameter （BPD, mm）, abdominal circumference （AC, mm） and femur length （FL, mm）. The measures were duplicate in each indicator taking the average of 3 times. The abdominal circumferences were measured by two methods. the first was the traditional measurement method: Standard one: The third edition of Ultrasound in Medicine standards described in abdominal circumference measurement plane, the liver and intrahepatic left branch of portal vein of the umbilical part were included, portal vein was shown with fetal abdominal wall on both sides of the basic equi-distant, human umbilical vein length was about 1/3 of fetal abdominal anteroposterior diameter, and the plane was vertical to the spine. Measurements had to include the fetal skin and were recorded as AC₁. The second was a new simple measurement method: Standard Two: The largest abdominal circumference plane with the bubble of the stomach, liver and vertical to the spine need not show umbilical vein, and in this level the heart and kidneys should not appear. Measurements had to include fetal skin and were recorded as AC₂. The trackball along the outer edge of the fetal abdomen was used directly to measure. Biparietal diameter and femur length were measured with internal and overseas common method. Fetal weight is estimated by the following formulas （Y express fetal weight, unit:g）:Formulas associated with single indicator:①associated with BPD:Y = 51.43×BPD-1516.9②associated with femur length:Y = 2616.26 +82.419×FL③associated with abdominal circumference:Y = 25.2×AC-1713.3 （AC = 223mm）Y = 29.6×AC-2918.6 （AC <223mm）Y = 27.3×AC +20.3×FL-3814.6 （suspected IUGR）Formulas associated with two or more indicators: ④associated with biparietal diameter and abdominal circumference:Log10Y = 1.599 +0.144×BPD +0.032×AC-0.111×BPD×AC/1000⑤associated with biparietal diameter, femur length and abdominal circumference:Log10Y = 1.4787-0.003343×AC×FL +0.001837×BPD +0.0458×AC +0.158×FL4 Birth weight and diameter line measurement: Exposed body weights were measured within 30 minutes after birth immediately by the same person, accurately read to 5 g, with Type RTZ-10A weighing machines made in Wuxi City and neonatal biparietal diameter （bilateral parietal bone distance between the most outer edge）, femur length （the distance between the two distal femur） and abdominal circumference （around the umbilical one-week distance） were measured with a ruler.5 Absolute error value of antenatal and postnatal fetal weight equal to or less than 250 g indicated coincident prediction. While the value more than 250 g were recorded as not in line with the prediction （absolute error value = actual body weight- predicted body weight）.6 All dates were analyzed with statistical analysis software SPSS13.0. All dates were expressed in （x|-）±S, and homogeneity of variance test, t test, single factor and the randomized block analysis of variance, x² test and correlation analysis were applied. P <0.05 was taken as statistically significant difference test.Results1 Measurements of the path lines by ultrasound and after birth had no significant differences in contrast （P> 0.05）.2 Comparing the unit linear correlation between various fetal single indicator and neonatal birth weight, abdominal circumferences and birth weights were of the highest correlation coefficient, contrast with femur length and biparietal diameter, there were statistics differences in correlation coefficient （P<0.05）. Between the two kinds of abdominal circumference measurements there were no statistics differences in correlation coefficient（P> 0.05）. A number of indicators and birth weights were of the highest correlation coefficient, but there was no significant difference between the BPD + AC group and the BPD + AC + FL group in correlation coefficient （P > 0.05）.3 Among single indicator equation the AC group had a distinct advantage than the BPD or FL Group （P<0.05） , but significantly lower than a number of indicators group （P<0.05） . Double indicators BPD + AC group and multiple indicators BPD + AC + FL Group had also statistics difference （P<0.05）, the latter a more accurate prediction of fetal weight.4 Neonatal weights were divided into <2500g group, 2500-3999g group, and = 4000g group. Absolute error comparisons of fetal weight predictions between the three groups were of statistics difference （P<0.05）, 2500-3999g group’s absolute error was lower. Specific line between two groups comparisions: 2500-3999g group had statistics difference with the other two groups （P <0.05）, while there were no statistics differences between <2500g group and = 4000g group（P> 0.05）.5 Absolute error analysis between two kinds of abdominal circumference measurements for fetal weight prediction: Between BPD + AC₁ group and BPD + AC₂ group, absolute error of estimated fetal weight values had no statistics difference in two methods of abdominal circumference measurements （P > 0.05）; Between BPD + AC₁ + FL group and the BPD + AC₂ + FL group, absolute error of estimated fetal weight values had no statistics difference in two methods of abdominal circumference measurements either（P> 0.05）.6 Coincident rates comparison of two kinds of abdominal circumference measurements for fetal weight prediction: Coincident rates of two kinds of abdominal circumference measurements for fetal weight prediction had no statistics difference in BPD + AC₁ group and BPD + AC₂ group （P > 0.05）; Coincident rates of two kinds of abdominal circumference measurements for fetal weight prediction had no statistics difference in BPD + AC₁ + FL group and BPD + AC₂ + FL group （P > 0.05）.7 Different body weight prediction results comparision of the different sex with a number of indicators: In 500 cases of the fetus, the boys were 266 and the girls were 234. Contrast to the estimated weight, the actual weight was heavier in boy group and lighter in girl group. When absolute error less than or equal to 250g, the girls group was higher than boys group, but the differences between the two groups were of no statistical significance （P> 0.05）.Conclusion1 Between various single indicator AC was of the best prediction accuracy of the fetus weight, and had the highest linear correlation coefficient with newborn birth weight, superior to BPD and FL Group.2 Fetal weight could be estimated more accurately with multiple indicators such as biparietal diameter, femur length and abdominal circumference.3 The two methods of abdominal circumference measurement estimated fetal weight with no statistical difference, that is, we can safely adopt a more easy way, measurement standard two to measure the fetal abdominal circumference for fetal weight estimation.4 With the same measurement value, boys had larger birth weight than girls, although there was no statistical significant difference. But if this factor was considered when estimating or set up the formula for calculating the gender dimension, the prediction accuracy would be improved.5 The current prediction methods were effected by measuring time and the neonatal birth weight. Babies born 3～4 days after prediction had a better accuracy. And prediction accuracy of newborns of normal body weight was significantly higher than the newborns of larger or smaller birth weight. The second part:The relation between fetal abdomen circumference survey by Ultrasound and fetal macrosomiaObjects and methods1 Healthy pregnant women with a single child or twins from January 2007 to June 2008 at our hospital were randomly selected for prenatal ultrasound examination and delivery in 72 hours after inspection at my department. Stand part of the study was excluded from pregnancy complications, as well as prenatal ultrasonography of obvious fetal malformations. A total of 436 cases were selected, aged at 20～41 years old, an average of （27.1±4.3） years, with≥37weeks gestational age, an average of （39.2±2.7） weeks. After birth the neonatals were weighted within 30 minutes, and fetal macrosomia as the observe group, the other fetals as the contrast group.2 Instruments were same with the first part..3 The fetal with birth weight≥4000g as macrosomia.4 Pregnant women were in supine position, taking conventional obstetric ultrasound examination to exclude fetal malformations. In 72 hours before delivery, the same physician who mastered the skills of ultrasound measurement estimated the fetal biparietal diameter （BPD, mm）, abdominal circumference （AC, mm） and femur length （FL, mm）. The standards of each index were same with the first part,and the abdominal circumferences were measured by the traditional measurement method: the third edition of Ultrasound in Medicine standards described in abdominal circumference measurement plane. The formulas of the fetal weight was same with the formulas associated with single indicator in the first part. At the same time we collect the pregnant women’s age, height, weight and gestational age.5 All dates were analyzed with statistical analysis software SPSS13.0. All dates were executed correlation analysis, the fixed amount dates used t test, the compare of count dates in different groups used x² test, the sensitivity and specificity was calculated by 2×2 table. P <0.05 was taken as statistically significant difference test.Results1 In this study, 436 newborns were detected by ultrasound. There were 86 cases of macrosomia that the fetal birth weight≥4000g, 62 cases were boys and 24 were girls, the proportion was 2.58: 1. The age and abdominal circumference of pregnant women had no statistics difference （P> 0.05）. The height, the height of uterine fundus, the weight before delivery and the increase extent of weight during gestational period had statistics difference （P<0.05）. The proportion of pregnant women live in city was 87% in the macrosomia group, 43% in the contrast group.2 The rate of extension pregnancy（≥40weeks, <42weeks） in observe group was higher than contrast group, it had statistics difference （x²=32.80, P<0.05） . The rate of postterm pregnancy（≥42 weeks） in this two groups had no statistics difference (（x²=2.708, P> 0.05）.3 The rate of cesarean section in observe group was higher than contrast group, it had statistics difference （P<0.05）.4 The metal’s BPD, AC, FL had linear correlation with macrosomia’s birth weight. Correlation coefficient rvalue were 0.59257、0.76179、0.60255.5 The rate of macrosomia was obviously increase when BPD≥95mm, AC≥350mm, FL≥75mm,and the sensitivity, positive predictive value, negative predictive value were highest when AC≥350mm. The specificity of macrosomia prediction reached 97.1% when AC≥370mm.Conclusion1 Artificial factors such as overmuch nutrition nourish and less movement during pregnancy were closely related to the occurrence of macrosomia, and had no much relationship with the age of the mothers. Non-diabetic obese pregnant wonmen had more opportunity to have a macrosomia baby. By the effect of genetic factors, the rate of the occurrence of macrosomia was higher when the parents were tall and obesity.2 The extension and postterm pregnancy were very important obstetric-pathological factors in the occurrence of macrosomia, clinical medical intervention can significantly reduce the incidence of macrosomia.3 The single indicator AC had a good linear correlation with macrosomia birth weight, it was higher then BPD and FL. The rate of macrosomia was obviously increase when AC≥350mm, AC≥370mm can be used as a single index in macrosomia prediction.4 Macrosomia is not a contraindication of vaginal delivery, Obstetricians should specific binding the different fetal size and maternal pelvic to decide the individual delivery manner. Some of macrosomia are expected successful delivery through vagina under closely observation in the stage of labor.更多还原