First-trimester screening for large-for-gestational-age infants

Abstract

Objectives: To examine the relationship between newborn birth weight and first-trimester uterine artery (UtA) pulsatility index (PI), maternal characteristics, serum pregnancy-associated plasma protein-A (PAPP-A), free β-human chorionic gonadotropin (β-hCG) and fetal nuchal translucency (NT) thickness. We also examined the results of screening for large-for-gestational-age (LGA) neonates by an integrated first-trimester approach incorporating these parameters.

Methods: We evaluated maternal characteristics, fetal NT, PAPP-A, free β-hCG and UtA-PI in 2097 singleton pregnancies at 11 + 0 to 13 + 6 weeks' gestation. Linear models based on quasi Akaike's Information Criterion were used to determine the best predictive model for fetal birth weight. The patient-specific risk of delivering an LGA infant was derived from multiple logistic regression analysis and the performance of screening was determined by receiver-operating characteristics curve analysis.

Results: The best predictive models for fetal birth weight included UtA-PI, PAPP-A, NT, parity, maternal age, smoking status, weight, height and free β-hCG. In pregnancies delivering LGA newborns compared with non-LGA pregnancies, PAPP-A and NT thickness were significantly increased (P = 0.016 and 0.001, respectively) and UtA-PI was significantly decreased (P = 0.011). A combination of maternal factors with PAPP-A, fetal NT and UtA-PI identified 34.4% of LGA newborns for a false-positive rate of 10%.

Conclusions: This study showed an association between newborn birth weight and maternal factors, and first-trimester PAPP-A, β-hCG, fetal NT and UtA-PI. Together, these factors can be used to identify over a third of pregnancies that will deliver LGA infants.