Second and third trimester fetal ultrasound population screening for risks of preterm birth and small-size and large-size for gestational age at birth: a population-based prospective cohort study

Abstract

Background: Preterm birth, small size for gestational age (SGA) and large size for gestational age (LGA) at birth are major risk factors for neonatal and long-term morbidity and mortality. It is unclear which periods of pregnancy are optimal for ultrasound screening to identify fetuses at risk of preterm birth, SGA or LGA at birth. We aimed to examine whether single or combined second and third trimester ultrasound in addition to maternal characteristics at the start of pregnancy are optimal to detect fetuses at risk for preterm birth, SGA and LGA. Methods: In a prospective population-based cohort among 7677 pregnant women, we measured second and third trimester estimated fetal weight (EFW), and uterine artery pulsatility and umbilical artery resistance indices as placenta flow measures. Screen positive was considered as EFW or placenta flow measure < 10th or > 90th percentile. Information about maternal age, body mass index, ethnicity, parity, smoking, fetal sex and birth outcomes was available from questionnaires and medical records. Screening performance was assessed via receiver operating characteristic (ROC) curves and area under the curve (AUC) along with sensitivity at different false-positive rates.

Maternal metabolic profiling to assess fetal gestational age and predict preterm delivery: a two-centre retrospective cohort study in the US

“…Open access and third trimester US for an estimation of risk of preterm birth (PTB), [7][8][9] to date these measures have not been widely adopted, are subject to user experience and have reported variable performance characteristics. The availability and expertise of US in disadvantaged areas is limited.…”

Prediction of Small-For-Gestational-Age Neonates at 33-39 Weeks’ Gestation in China: Logistic Regression Modeling of The Contributions of Second- and Third-Trimester Ultrasound Data and Maternal Factors

“…Most EFW formulas show a strong correlation between the predicted weight and actual birth weight (r > 0.9, 19/21 formulas) [6]. The area under the curve (AUC) for predictions based on EFW measurements in the mid-trimester or third-trimester ultrasound was 0.69~0.72 and 0.79, respectively [9,10]. The combination of an EFW model in the second and third trimesters along with assessment of maternal factors (MF) and placental ow measurements can improve the screening results for SGA (AUC, 0.84; 95%CI 0.82-0.87) [10].…”

“…The area under the curve (AUC) for predictions based on EFW measurements in the mid-trimester or third-trimester ultrasound was 0.69~0.72 and 0.79, respectively [9,10]. The combination of an EFW model in the second and third trimesters along with assessment of maternal factors (MF) and placental ow measurements can improve the screening results for SGA (AUC, 0.84; 95%CI 0.82-0.87) [10]. Ciobanu et al showed that the AUC of EFW measurements was 0.883 at 35 and 36 weeks of gestation, while the AUC for births that occurred within two weeks of the evaluation could be as high as 0.933 [11].…”

Fetal growth restriction

“…The main goal of a first trimester model is to identify the women at risk for severe early phenotype (FGR-I) and to enable early initiation of therapeutic intervention to alter the course the disease, as has been shown in the meta-analysis of nine trails on the use of aspirin (including 1317 women) [67], and a recent large international RCT (Aspre trial) [68]. Conversely, prediction models in the third trimester can help to optimize monitoring and 9 timing of delivery in pregnancies with suspected late FGR-II [69][70][71]. Figure 2 shows a proposed model for screening and follow-up of suspected FGR in each trimester of pregnancy using maternal characteristics (MC), doppler, biometry and biomarker measurements.…”

“…During the third trimester, prediction models generally have better predictive ability due to being temporally closer to the onset of clinical disease. In a prospective population-based cohort among 7,677 pregnant women, the detection of fetuses at risk for adverse birth outcomes nearly doubled, with the implementation of third trimester fetal ultrasound scan, combined with maternal characteristics, compared with only second trimester ultrasound [70]. Prediction models can also be improved because of the composition of the model (addition of biomarkers and/or growth velocity).…”