The Impact of First-Trimester Serum Free β-Human Chorionic Gonadotropin and Pregnancy-Associated Plasma Protein A on the Diagnosis of Fetal Growth Restriction and Small for Gestational Age Infant

Abstract

Objective: To evaluate the risk of fetal growth restriction (FGR) associated with first-trimester maternal serum concentrations of pregnancy-associated plasma protein A (PAPP-A) and free β-human chorionic gonadotropin (β-hCG). Methods: A longitudinal study of 2,178 women who underwent first-trimester evaluation of serum PAPP-A and free β-hCG. FGR was defined as a decrement of the fetal abdominal circumference to below the 10th percentile of our standard growth curve in the presence of Doppler signs of impaired placental perfusion. Logistic regression was used to compute multivariable odds ratios and the estimated prevalences of outcomes associated with first-trimester serum marker concentrations. Results: The prevalences of small for gestational age (SGA, <10th percentile birth-weight) neonates and FGR were significantly higher among women with serum PAPP-A concentrations below the 10th percentile than in controls: 40/206 compared to 183/1,928, for SGA, adjusted odds ratio = 2.1, 95% confidence intervals (CI) 1.4–3.03; 24/75 compared to 182/1,900, for FGR, adjusted odds ratio = 3.9, 95% CI 2.3–6.5. The adjusted prevalences of FGR and SGA among women with simultaneous low first-trimester values of PAPP-A and free β-hCG were 0.21 (95% CI 0.13–0.33) and 0.26 (95% CI 0.17–0.36), respectively. Conclusion: Low first-trimester maternal serum PAPP-A concentrations are significantly associated with reduced fetal size and increased risk of FGR with Doppler signs of impaired placental perfusion.