Establishment Of Neonatal Birth Weight Centile Curves In This Region And First-trimester Screening For Small-for-gestational-age

BACKGROUND:Neonatal birth weight is the easiest indicator for assessing neonatal maturity and prognosis.Small for gestational age(SGA)is usually defined as whose birth weight is lower than the 10th percentile of corresponding gestational age birth weight,and often associated with adverse pregnancy outcomes.Establishing a accurate centile curves of neonatal birth weight in this region helps to identify SGA and assess the neonatal development accurately.An effective screening model at the first trimester for SGA helps to identify high-risk women prenatally,and then strengthen prenatal management to reduce the occurrence of adverse outcomes.OBJECTIVE:To establish a neonatal birth weight centile curves and compare it with the commonly used birth weight reference curves;to analyze the risk factors of SGA,and evaluate the predictive performance of the combined risk model in screening SGA at the first trimester.Analyze the relationship between SGA and adverse pregnancy outcomes,strengthen SGA management,and reduce the occurrence of adverse outcomes.METHODS:(1)The data for this study were derived from a continuous,non-selective prospective cohort study in women attending for their routine first hospital visit at 11 weeks to 13 weeks 6 days of gestation.We recorded maternal characteristics and performed a transabdominal ultrasound scan to confirm gestational age,measure their bilateral uterine artery pulsation index,and collected their blood samples for testing placental growth factor and pregnancy-associated protein-A.Mean arterial pressure is measured at the same time,then follow up and analysis their pregnancy outcomes.(2)Using the LMS method to fit the birth weight curve of newborns,and compare it with commonly used birth weight reference curves;further analyze the high risk factors of SGA,combine the different indicators to establish a predictive SGA model,and evaluate each model’s predictive value.(3)Statistical tools and methods:All data were entered into the viewpoint6.0 software database,and statistical analysis and birth weight curve fitting were performed using SPSS 23.0 and R language 3.5.2 and RStudio 1.1.463.The birth weight curve was fitted by LMS method,and the goodness of fit was judged by residual analysis and Q-Q diagram.The area under the receiver operating characteristic curve is used as the index to evaluate the predictive value of the model,and the sensitivity and specificity are used as indicators to judge the diagnostic value of the categorical variables.RESULTS:(1)Up to February 28,2019,a total of 1800 patients were enrolled and completed their follow-up.Among them,32 cases spontaneous abortion or fetal death,15 cases terminal of pregnancy for fetal structural abnormality or chromosomal abnormality,2 cases terminal of pregnancy for severe maternal diseases,1 case terminal of pregnancy for social reasons,3 cases loss to follow-up,3 cases lack of important data such as neonatal birth weight or gender.The effective data for the final analysis of neonatal weight was 1745 cases.Of those 1745 cases,65 had missing screening index data,so the effective data for the final SGA predictive value analysis was 1680.(2)Birth weight centile curves establishment:1745 live births,98 cases(5.62%)premature birth,66 cases(3.78%)low birth weight.The 50th percentile curve of the birth weight of the newborn was well matched with the Fetal Medicine Foundation recommending curve and the American College of Obstetricians and Gynecologists recommending curve in the post-term stage,showing no significant differences.(3)Screening for SGA:The detection rate of combined model for SGA with PE was 62.3%,for SGA without PE was 25.3%,at the false positive rate of 10%.The specificity of SGA to adverse pregnancy outcomes is high,but the sensitivity is generally low,fluctuating from 12.5-30.0%.CONCLUSION:The birth weight of term neonates in this center is the same as the international common curves.There is no racial difference at present.Combined maternal history with placental function indicators to screening for SGA at the first trimester has certain value.Screening and strengthening management of SGA has a certain significance in reducing the incidence of adverse pregnancy outcomes,but SGA is less sensitive to the judgment of adverse outcomes.Further research needs to focus on more related and more sensitive indicators of adverse outcomes.