Evaluation of screening performance of first-trimester competing-risks prediction model for small-for-gestational age in Asian population.

OBJECTIVE: To examine the external validity of the Fetal Medicine Foundation (FMF) competing-risks model for the prediction of small-for-gestational age (SGA) at 11-14 weeks' gestation in an Asian population. METHODS: This was a secondary analysis of a multicenter prospective cohort study in 10 120 women with a singleton pregnancy undergoing routine assessment at 11-14 weeks' gestation. We applied the FMF competing-risks model for the first-trimester prediction of SGA, combining maternal characteristics and medical history with measurements of mean arterial pressure (MAP), uterine artery pulsatility index (UtA-PI) and serum placental growth factor (PlGF) concentration. We calculated risks for different cut-offs of birth-weight percentile (< 10th , < 5th or < 3rd percentile) and gestational age at delivery (< 37 weeks (preterm SGA) or SGA at any gestational age). Predictive performance was examined in terms of discrimination and calibration. RESULTS: The predictive performance of the competing-risks model for SGA was similar to that reported in the original FMF study. Specifically, the combination of maternal factors with MAP, UtA-PI and PlGF yielded the best performance for the prediction of preterm SGA with birth weight < 10th percentile (SGA < 10th ) and preterm SGA with birth weight < 5th percentile (SGA < 5th ), with areas under the receiver-operating-characteristics curve (AUCs) of 0.765 (95% CI, 0.720-0.809) and 0.789 (95% CI, 0.736-0.841), respectively. Combining maternal factors with MAP and PlGF yielded the best model for predicting preterm SGA with birth weight < 3rd percentile (SGA < 3rd ) (AUC, 0.797 (95% CI, 0.744-0.850)). After excluding cases with pre-eclampsia, the combination of maternal factors with MAP, UtA-PI and PlGF yielded the best performance for the prediction of preterm SGA < 10th and preterm SGA < 5th , with AUCs of 0.743 (95% CI, 0.691-0.795) and 0.762 (95% CI, 0.700-0.824), respectively. However, the best model for predicting preterm SGA < 3rd without pre-eclampsia was the combination of maternal factors and PlGF (AUC, 0.786 (95% CI, 0.723-0.849)). The FMF competing-risks model including maternal factors, MAP, UtA-PI and PlGF achieved detection rates of 42.2%, 47.3% and 48.1%, at a fixed false-positive rate of 10%, for the prediction of preterm SGA < 10th , preterm SGA < 5th and preterm SGA < 3rd , respectively. The calibration of the model was satisfactory. CONCLUSION: The screening performance of the FMF first-trimester competing-risks model for SGA in a large, independent cohort of Asian women is comparable with that reported in the original FMF study in a mixed European population. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Screening for morbidly adherent placenta in early pregnancy.

OBJECTIVE: To estimate the diagnostic accuracy of a two-stage strategy for early prediction of morbidly adherent placenta (MAP). In the first stage, at 11-13 weeks' gestation, women with low-lying placenta and history of uterine surgery are classified as being at high risk for MAP and, in the second stage, at 12-16 weeks, these high-risk pregnancies are assessed at a specialist MAP clinic. METHODS: This was a prospective study in women having an ultrasound scan at 11-13 weeks' gestation as a part of routine pregnancy care. Women with low-lying placenta and a history of uterine surgery were followed up at a specialist MAP clinic at 12-16 weeks' gestation, 20-24 weeks and 28-34 weeks. At each visit to the MAP clinic, an ultrasound scan was carried out and the following features suggestive of MAP were recorded: non-visible Cesarean section scar; bladder wall interruption; thin retroplacental myometrium; presence of intraplacental lacunar spaces; presence of retroplacental arterial-trophoblastic blood flow; and irregular placental vascularization demonstrated by three-dimensional power Doppler. RESULTS: Screening at 11-13 weeks was carried out in 22 604 singleton pregnancies, 1298 (6%) of which were considered to be at high risk of MAP because they had previous uterine surgery and low-lying placenta. At the MAP clinic at 12-16 weeks, the diagnosis of MAP was suspected in 14 cases and this was confirmed at delivery in 13. In the rest of the population, there were no cases of MAP. CONCLUSION: Accurate prediction of MAP can be achieved by ultrasound examination at 12-16 weeks' gestation. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Prediction of stillbirth from maternal factors, fetal biometry and uterine artery Doppler at 19-24 weeks.

OBJECTIVES: To evaluate the performance of screening for all stillbirths and those due to impaired placentation and unexplained or other causes using a combination of maternal factors, fetal biometry and uterine artery pulsatility index (UtA-PI) at 19-24 weeks' gestation and to compare this performance with that of screening by UtA-PI alone. METHODS: This was a prospective screening study of 70 003 singleton pregnancies including 69 735 live births and 268 (0.38%) antepartum stillbirths; 159 (59%) were secondary to impaired placentation and 109 (41%) were due to other or unexplained causes. Multivariable logistic regression analysis was used to develop a model for prediction of stillbirth based on a combination of maternal factors, fetal biometry and UtA-PI. RESULTS: Combined screening predicted 55% of all stillbirths, including 75% of those due to impaired placentation and 23% of those that were unexplained or due to other causes, at a false-positive rate of 10%. Within the impaired placentation group, the detection rate of stillbirth < 32 weeks' gestation was higher than that of stillbirth ≥ 37 weeks (88% vs 46%; P < 0.001). The performance of screening by the combined test was superior to that of selecting the high-risk group on the basis of UtA-PI > 90th percentile for gestational age, which predicted 48% of all stillbirths, 70% of those due to impaired placentation and 15% of those that were unexplained or due to other causes. CONCLUSIONS: Second-trimester screening by a combination of UtA-PI with maternal factors and fetal biometry can predict a high proportion of stillbirths and, in particular, those that are due to impaired placentation. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.