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Conference Proceeding

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American Journal of Obstetrics and Gynecology


OBJECTIVE: Studies have suggested a role for biophysical markers (BPM) including uterine artery Doppler (UAD) and maternal mean arterial pressure (MAP) in prediction of neonatal SGA. We sought to determine if the addition of flow velocities in spiral artery (SA), UAD, MAP and maternal risk factors could improve prediction of neonatal SGA, compared with using maternal risk factors alone. STUDY DESIGN: This is a prospective longitudinal study over a 5-year period. We measured SA UAD and MAP at: 11 to 13 + 6, 18 to 22 + 6/7 and 28 to 34+ 6/7 weeks of gestation. Prediction models for SGA were constructed using backward and forward logistic regression including minor and major maternal risk factors for SGA (RCOG Green top guideline #31: RCOG 2014) alone; and when combined with BPM. SA, UAD Doppler indices and MAP, converted to z-scores adjusted for gestational age (GA). Crown rump length and estimated fetal weight were included in the model as appropriate for the GA. SGA was defined as birth weight < 10th percentile for GA. Goodness of fit of the models were assessed using Hosmer-Lemeshow test. Area under ROC curves (AUC) were used to compare the detection rates between the models. RESULTS: Among 581 pregnancies included, 43 (7.4%) had SGA neonates. The model using maternal risk factors only detected 53.5% of neonates with SGA. Including BPM resulted in an improvement in sensitivity of the second and third-trimester models: 65.8% and 72.5%, respectively and the specificity: 79.4% and 81.8% for second and third trimesters, respectively. The resulting increase in the AUC between using maternal risk factors, 0.70; and the third-trimester prediction model 0.80, was statistically significant, p< 0.004. (Table). CONCLUSION: When compared with using maternal risk factors alone, models incorporating BPM such as the spiral artery, uterine artery Doppler and mean arterial pressures result in improved prediction of SGA, particularly in early third trimester.




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