Comparison Of The Accuracy Of Different Formulas For Predicting Term Fetal Weight

Background:Fetal weight is an important parameter to monitor fetal growth and development during the perinatal period and a key factor in determining the mode of delivery.Since 2010,data released by the world health organization show that China has become the country with the highest rate of cesarean section in the world.In order to ensure the safety of mother and child,it has always been the goal of Chinese obstetricians to reduce the cesarean section rate.Prenatal prediction of fetal weight abnormalities can be used to timely find out if a pregnant woman will have complications,such as diabetes,fetal growth restriction,thrombophilia,gestational hypertension,etc.Both large fetuses and intrauterine growth restrictions increase perinatal morbidity and the risk of long-term neurodevelopmental disorders.The diagnosis of fetal largeness during labor often leads to vaginal delivery failure and shoulder dystocia,and the pregnancy often needs to be terminated by a cesarean section.Therefore,an accurate estimation of fetal weight is crucial to the optimization of safe prenatal and prenatal management.This study tried to compare the methods of predicting the accuracy of full-term fetal weight by different formulas,so as to select a relatively accurate formula suitable for pregnant women in Jilin region,and provide a basis for improving the management of pregnancy.Objective:This paper discusses the most appropriate formula for predicting fetal weight at37⁺¹-41⁺⁶ weeks of gestation in Jilin area,compares the accuracy of different formulas for estimating fetal weight,and recommends the formula with the highest accuracy as the clinical reference for obstetricians.This will provide a relatively accurate basis for the decision of delivery mode and the timing of termination of pregnancy.A comparison of the actual weight at birth and the weight determined within three days before birth by ultrasound records was made,and different formulas were used to estimate the fetal weight and its influencing factors.An accurate formula to determine fetus weight will help clinical obstetrics and gynecologists to provide a more accurate basis,to monitor the growth of the fetus and reduce prenatal morbidity and mortality.This will also reduce birth injury,postnatal complications and other adverse outcomes,and improve the quality of obstetric management.Materials and Methods:Retrospective analysis was performed on 3057 pregnant women who gave birth in the obstetrics department of China-Japan alliance hospital of the Jilin university from January 2016 to December 2019.Those with pregnancy complications or a fetus with structural abnormalities or chromosomal abnormalities in ultrasound examination were excluded.The pregnant women had an average age of 29.54±3.92 years.The gestational age ranged from 37⁺¹-41⁺⁶ weeks.The newborn was weighed on a standard electronic scale within 30 minutes after birth.All the included women underwent fetal examination under ultrasound within 0-3 days in the prenatal period,and all the measured ultrasound parameters were recorded,including biparietal diameter（BPD）,abdominal circumference（AC）,head circumference（HC）,femur length（FL）,amniotic fluid index（AFI）,etc.At the same time,the clinical parameters of pregnant women were recorded,which included maternal age,gestational history,gestational weeks,height,weight,uterine height,abdominal circumference,and weight gain during pregnancy.The formulas commonly used in the world to estimate fetal weight were used and the calculated results were compared with the actual birth weighed（ABW）.A total of 3057 fetal records were obtained and divided into whole group 3057,normal weight group（2500g≤ABW<4000g）2315,and macrocephaly group（ABW≥4000g）735.Microsoft Excel2019 was used to maintain the database,and SPSS25.0 was used for data analysis.The data were tested for normality.The measurement data conforming to normal distribution were expressed as（x±s）,and an independent sample’s t-test was used for inter-group comparison.The variables that did not conform to the normal distribution were represented by M（p25-p75）,and the Wilcoxon rank-sum test was used for inter-group comparisons.The quantitative data were expressed by n（%）,andχ² was used for comparison between the groups.A logistic regression model was established,and the ROC curve was used to evaluate the diagnostic efficacy of macrocephaly.P<0.05 was considered statistically significant,and the test level（α）was taken as 0.05.Results:1.Among the six regression equations of clinical parameters,the Lamella-Roda method had the highest accuracy in estimating fetal weight,both in the overall group and in the normal-weight group.The second one is the method of selection.In the macrosomia group,the accuracy of Zeng Weiyue method in evaluating fetal weight was higher than the other five methods.2.Among the 20 commonly used regression equations of ultrasonic parameters,HandLock I was the best in predicting the fetal birth weight in the whole group and the normal weight group.On the other hand,HandLock III was the best predictor for macrosomia.3.Various parameters were used to predict the ROC curve of macrosomia:among the clinical parameters,the area under the ROC curve of uterine height was the largest,and the sensitivity and specificity were higher,which could be used as an index for the clinical prediction of macrosomia.Among the ultrasonic parameters,the abdominal circumference（AC）offers the largest area under ROC with high sensitivity and specificity.AC is a conventional index used in ultrasonic examination and measurement;it is easy to obtain and serves as an index in ultrasound for the prediction of macrosize.4.Analysis of relevant factors for the occurrence of macrosomia:it was concluded that age,birth order,gestational weeks,pre-pregnancy body mass index,weight gain during pregnancy,and amniotic fluid index are independent risk factors for macrosomia.In other words,higher age,birth order,gestational weeks,gestational body mass index,weight gain during pregnancy,and amniotic fluid index are risk factors of macrosomia.Conclusion:1.Different clinical and ultrasonic formulas should be used to predict fetal weight in normal weight children and macrosomia children,so as to improve the prediction accuracy.2.Abdominal circumference（AC）and uterine height are the best ultrasound parameters to predict macrocephaly.3.The greater the age,number of births,gestational age,pre-pregnancy body mass index,weight gain during pregnancy,and amniotic fluid index,the higher the risk of macrosomia.