A Study About Reference Ranges Of Guangdong Fetal Head Circumference And To Construct A Reference Curve

Objective:To improve the assessment of fetal head size and identify the fetuses with small head accurately,a new reference range and percentile curve of fetal head circumference for local population was constructed.Methods:This was a retrospective,cross-sectional study of singleton pregnancies with confirmed gestational ages.The fetal head circumference result in Guangdong Women and Children Hospital between September,2012 and December,2016 was recorded.Each fetus was selected only once for this study.In this study,it was mainly divided in two parts.Firstly,the Kappa value and Youden index of the five reference ranges was compared to assess their consistency with the actual development of local fetal head circumference,and the sensitivity and specificity of the five reference ranges when screening small head fetuses were evaluated.Secondly,for the fetal head circumference,percentiles regression models were fitted at each gestational age by using Cole's LMS method.The method indicates the fit of the model as measured by the deviances and the generalized version of Akaike Information Criterion with penalty equal to 3(GAIC(3)).Then the measurements were transformed into Z-scores to evaluate fitness.Result:1?Finally,a total of 18269 fetal head circumference records were collected.The average of pregnant women was 29 years old.Proportion of male and female fetuses was 53.1%and 46.9%,respectively.All the pregnant women in the study lived in Guangdong,97.5% of them were natives of Guangdong.2?The Kappa value and Youden index of the Chinese fetal reference ranges were 0.86 and 0.87 respectively,which were higher than those of the other four reference ranges.However,it's Youden index low at 23,28,and 40 gestational weeks.The total Kappa value of the Hadlock's standard was only 0.58,however,it had the highest consistency degree with the actual development of local fetal head circumference at 18-28 gestational weeks.The total Kappa values of screening fetuses with small head of the two international standards were 0.47 and 0.69.3?According to the generalized version of Akaike Information Criterion with penalty equal to 3(GAIC(3)),(1,19,18)was chosen as the best set of effective degrees of freedom of the L?M and S curves to model good-fitted and smoothed head circumference percentile curves.Differences between the actual percentiles and the fitted percentiles were no more than 0.6mm.The z-scores of all gestational week were under normal distribution.4.Male fetuses were more likely to have small heads than female fetuses.Mothers of fetuses with small head were younger than the mothers of fetuses with normal head.Conclusions:The Hadlock's standard was not suitable to evaluate local fetal head circumference.Moreover,both the international standard and the national standard fail to evaluate local fetal head development overall.It's time to update the reference ranges of fetal head circumference for local population.The reference ranges of local fetal head circumference constructed in this study by LMS method was available for clinical use or research.