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1.
Ultrasound Obstet Gynecol ; 59(2): 177-184, 2022 Feb.
Article in English | MEDLINE | ID: mdl-34214232

ABSTRACT

OBJECTIVES: First, to investigate the additive value of second-trimester placental growth factor (PlGF) for the prediction of a small-for-gestational-age (SGA) neonate. Second, to examine second-trimester contingent screening strategies. METHODS: This was a prospective observational study in women with singleton pregnancy undergoing routine ultrasound examination at 19-24 weeks' gestation. We used the competing-risks model for prediction of SGA. The parameters for the prior model and the likelihoods for estimated fetal weight (EFW) and uterine artery pulsatility index (UtA-PI) were those presented in previous studies. A folded-plane regression model was fitted in the dataset of this study to describe the likelihood of PlGF. We compared the prediction of screening by maternal risk factors against the prediction provided by a combination of maternal risk factors, EFW, UtA-PI and PlGF. We also examined the additive value of PlGF in a policy that uses maternal risk factors, EFW and UtA-PI. RESULTS: The study population included 40 241 singleton pregnancies. Overall, the prediction of SGA improved with increasing degree of prematurity, with increasing severity of smallness and in the presence of coexisting pre-eclampsia. The combination of maternal risk factors, EFW, UtA-PI and PlGF improved significantly the prediction provided by maternal risk factors alone for all the examined cut-offs of birth weight and gestational age at delivery. Screening by a combination of maternal risk factors and serum PlGF improved the prediction of SGA when compared to screening by maternal risk factors alone. However, the incremental improvement in prediction was decreased when PlGF was added to screening by a combination of maternal risk factors, EFW and UtA-PI. If first-line screening for a SGA neonate with birth weight < 10th percentile delivered at < 37 weeks' gestation was by maternal risk factors and EFW, the same detection rate of 90%, at an overall false-positive rate (FPR) of 50%, as that achieved by screening with maternal risk factors, EFW, UtA-PI and PlGF in the whole population can be achieved by reserving measurements of UtA-PI and PlGF for only 80% of the population. Similarly, in screening for a SGA neonate with birth weight < 10th percentile delivered at < 30 weeks, the same detection rate of 90%, at an overall FPR of 14%, as that achieved by screening with maternal risk factors, EFW, UtA-PI and PlGF in the whole population can be achieved by reserving measurements of UtA-PI and PlGF for only 70% of the population. The additive value of PlGF in reducing the FPR to about 10% with a simultaneous detection rate of 90% for a SGA neonate with birth weight < 3rd percentile born < 30 weeks, is gained by measuring PlGF in only 50% of the population when first-line screening is by maternal factors, EFW and UtA-PI. CONCLUSIONS: The combination of maternal risk factors, EFW, UtA-PI and PlGF provides effective second-trimester prediction of SGA. Serum PlGF is useful for predicting a SGA neonate with birth weight < 3rd percentile born < 30 weeks after an inclusive assessment by maternal risk factors and biophysical markers. Similar detection rates and FPRs can be achieved by application of contingent screening strategies. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.


Subject(s)
Fetal Growth Retardation/diagnosis , Pregnancy Trimester, Second , Ultrasonography, Prenatal/methods , Adult , Female , Fetal Growth Retardation/diagnostic imaging , Humans , Placenta Growth Factor/blood , Pregnancy , Prenatal Diagnosis/methods , Prospective Studies , Uterine Artery/diagnostic imaging , Young Adult
2.
BJOG ; 128(13): 2110-2115, 2021 Dec.
Article in English | MEDLINE | ID: mdl-34139043

ABSTRACT

OBJECTIVE: To examine the predictive performance of the relevant guideline by the Royal College of Obstetricians and Gynaecologists (RCOG) for neonates that are small for gestational age (SGA), and to compare the performance of the RCOG guideline with that of our competing risks model for SGA. DESIGN: Prospective observational study. SETTING: Obstetric ultrasound departments in two UK maternity hospitals. POPULATION: A total of 96 678 women with singleton pregnancies attending for routine ultrasound examination at 19-24 weeks of gestation. METHODS: Risks for SGA for different thresholds were computed, according to the competing risks model using maternal history, second-trimester estimated fetal weight, uterine artery pulsatility index and mean arterial pressure. The detection rates by the RCOG guideline scoring system and the competing risks model for SGA were compared, at the screen positive rate (SPR) derived from the RCOG guideline. MAIN OUTCOME MEASURES: Small for gestational age (SGA), <10th or <3rd percentile, for different gestational age thresholds. RESULTS: At an SPR of 22.5%, as defined by the RCOG guideline, the competing risks model predicted 56, 72 and 81% of cases of neonates that are SGA, with birthweights of <10th percentile, delivered at ≥37, <37 and <32 weeks of gestation, respectively, which were significantly higher than the respective figures of 36, 44 and 45% achieved by the application of the RCOG guideline. The respective figures for neonates that were SGA with birthweights of <3rd percentile were 66, 79, 85 and 41, 45, 44%. CONCLUSION: The detection rate for neonates that were SGA with the competing risk approach is almost double than that obtained with the RCOG guideline. TWEETABLE ABSTRACT: The competing risks approach for the prediction of SGA performs better than the existing RCOG guideline.


Subject(s)
Fetal Growth Retardation/diagnostic imaging , Guidelines as Topic , Infant, Small for Gestational Age , Ultrasonography, Doppler/methods , Ultrasonography, Prenatal/methods , Uterine Artery/diagnostic imaging , Adult , Arterial Pressure , Female , Fetal Growth Retardation/diagnosis , Fetal Weight , Gestational Age , Humans , Infant, Newborn , Predictive Value of Tests , Pregnancy , Pregnancy Trimester, Second , Prospective Studies , Pulsatile Flow
3.
Ultrasound Obstet Gynecol ; 57(6): 917-924, 2021 06.
Article in English | MEDLINE | ID: mdl-33464642

ABSTRACT

OBJECTIVE: To develop further a new competing-risks model for the prediction of a small-for-gestational-age (SGA) neonate, by including second-trimester ultrasonographic estimated fetal weight (EFW). METHODS: This was a prospective observational study in 96 678 women with singleton pregnancy undergoing routine ultrasound examination at 19-24 weeks' gestation. All pregnancies had ultrasound biometry assessment, and EFW was calculated according to the Hadlock formula. We refitted in this large dataset a previously described competing-risks model for the joint distribution of gestational age (GA) at delivery and birth-weight Z-score, according to maternal demographic characteristics and medical history, to obtain the prior distribution. The continuous likelihood of the EFW was fitted conditionally to GA at delivery and birth-weight Z-score and modified the prior distribution, according to Bayes' theorem, to obtain individualized distributions for GA at delivery and birth-weight Z-score and therefore patient-specific risks for any cut-offs for GA at delivery and birth-weight Z-score. We assessed the discriminative ability of the model for predicting SGA with, without or independently of pre-eclampsia occurrence. A calibration study was carried out. Performance of screening was evaluated for SGA defined according to the Fetal Medicine Foundation birth-weight charts. RESULTS: The distribution of EFW, conditional to both GA at delivery and birth-weight Z-score, was best described by a regression model. For earlier gestations, the association between EFW and birth weight was steeper. The prediction of SGA by maternal factors and EFW improved for increasing degree of prematurity and greater severity of smallness but not for coexistence of pre-eclampsia. Screening by maternal factors predicted 31%, 34% and 39% of SGA neonates with birth weight < 10th percentile delivered at ≥ 37, < 37 and < 30 weeks' gestation, respectively, at a 10% false-positive rate, and, after addition of EFW, these rates increased to 38%, 43% and 59%, respectively; the respective rates for birth weight < 3rd percentile were 43%, 50% and 64%. The addition of EFW improved the calibration of the model. CONCLUSION: In the competing-risks model for prediction of SGA, the performance of screening by maternal characteristics and medical history is improved by the addition of second-trimester EFW. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.


Subject(s)
Fetal Growth Retardation/diagnosis , Infant, Small for Gestational Age , Prenatal Diagnosis , Bayes Theorem , Biometry , Female , Fetal Weight , Humans , Infant, Newborn , Predictive Value of Tests , Pregnancy , Pregnancy Trimester, Second , Ultrasonography, Prenatal
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