The Associations Between The Preterm Birth Prediction And The Cervical Morphological Parameters Measured By Transvaginal Ultrasound In Second And Third-trimester Pregnancy

Objectives:Preterm birth is a global health problem causing perinatal infant death mostly and need to be solved urgently.In order to lower the perinatal mortality and morbidity,it is vital to predict without a clear pathogenesis and the ideal therapeutic effect of preterm labor.Nowadays,morphological parameters of cervix in ultrasound have been used as premature predictors widely due to its objectivity,simplicity and convenience.As we all known,human beings are the bipedal.When people lie down and accept ultrasonic tests,they will do Valsalva actions following our orders to increase abdominal pressure to simulate the cervical states in an upright position or advancing gestation.And we can assess whether the Valsalva action affects these cervical predictors’ prediction to preterm birth.At the same time,we will analyse the predictive values of cervical sonographic parameters,including cervical length(CL),anterior uterocervical angle(aUCA),posterior uterocervical angle(pUCA)and so on that we can find a new method to predict,prevent and treat the preterm labor.Methods:A total of 369 patients met inclusion criteria and were included in analysis,who accepted antenatal examinations regularly in the second affiliated hospital of kunming medical university between September 2019 and September 2020.Firstly,we recorded their basic information and medical histories.Then our trained and experienced doctors checked their cervix via transvaginal ultrasound to collected their cervical morphological parameters including Rest and Valsalva datas respectively in 3 periods(24～27+6 weeks,28～31+6 weeks and 32～36+6 weeks).But we analysed our datas divided into CL,aUCA,pUCA and their changing values(Rest values minus Valsalva values)respectively in 4 stages(24～27+6 weeks,28～31+6 weeks,32～33+6 weeks and 34～36+6 weeks).We divided these gravidas into full-term group(≥37 weeks)and preterm group(<37 weeks)according to their delivery gestational ages.Finally we uesd SPSS 20.0 to compare the differences beween their cervical morphological parameters during 2 states and in 4 stages(same as above mentioned).Results:1.When pregnant age is regarded as a risk factor predicting preterm birth,the difference of average age between the full-term and preterm groups isn’t statistically significant(P>0.05),and the difference of preterm birth rate between older(age≥35)and younger(age≥35)groups is not statistically significant(P>0.05).2.Full-term group in same stage:The differences between Rest and Valsalva values of CL,aUCA,pUCA are statistically significant(P<0.05).3.Full-term group in same state:(ⅰ)CL shortens with the increase of the pregnant stage and the differences between 4 stages are statistically significant(P<0.05)in Rest or Valsalva state.(ⅱ)About Rest aUCA and pUCA,the differences between first stage(24～27+6 weeks)and second stage(28～31+6 weeks)and the differences between first stage and fourth stage(34～36+6 weeks)are statistically significant(P<0.05);in addition,the difference of Rest aUCA between first stage and third stage is statistically significant(P<0.05).(ⅲ)The difference of Valsalva cervical funneling between first stage and fourth stage is statistically significant(P<0.05).4.Preterm group in same stage:The differences between Rest and Valsalva values of CL,aUCA,pUCA in first and second stages are statistically significant(P<0.05).While,the differences between Rest and Valsalva values of aUCA,pUCA in third stage are statistically significant(P<0.05).5.Comparison between full-term and preterm groups at same state in first stage:(ⅰ)The differences between Rest aUCA or Rest pUCA respectively are statistically significant(P<0.05);(ⅱ)About CL,aUCA,pUCA and CL changing value,the differences between their Valsalva values respectively are statistically significant(P<0.05).6.Comparison between full-term and preterm groups at same state in second stage:The difference between Valsalva pUCA is statistically significant(P<0.05).7.Comparison between CL≤2.0 cm and CL≤1.5 cm at 2 states in 4 stages respectively to predict preterm birth:(ⅰ)The highest positive predictive value is Valsalva values in all stages;(ⅱ)The highest positive predictive value is CL≤1.5 cm in first and third stage;(3)The highest positive predictive value is CL≤2.0 cm in second and fourth stages.Conclusions:1.The pregnant age(average age or age≥35)is not related to premature.2.The Rest and Valsalva values of full-term CL,aUCA and pUCA differ in second and third-trimester pregnancy.3.The Rest and Valsalva values of full-term CL decrease gradually with the increasing of gestational age,while preterm CL at 2 states doesn’t change obviously in second and third-trimester pregnancy.4.Valsalva CL and the changing value of CL are associated with preterm birth in first stage.When Valsalva CL≤1.5 cm is compared with Valsalva CL≤2.0 cm,the former is the higher positive predictive value,the later is the higher sensitive index.5.Both aUCA and pUCA at 2 states in first stage can be used as predictors for preterm birth.6.Valsalva pUCA is associated with preterm birth in second stage.7.Cervical funneling as a single predictor can’t increase the value for premature prediction in second and third-trimester pregnancy.