title: First trimester fetal ultrasound parameters associated with PAPP-A and fβ-hCG.
abstract: OBJECTIVE
  To study the association of fβ-hCG and PAPP-A measured at 11-14 weeks of gestation with delta crown-rump-length (dCRL), delta fetal heart rate (dFHR) and delta nuchal translucency (dNT). To calculate adjusted MoM taking into consideration these associations.
  
  
  METHODS
  Retrospective cross-sectional study on 5,536 singleton euploid pregnancies participating in a first trimester screening program for chromosomal abnormalities by nuchal translucency and maternal serum biochemistry. Adjusted MoM were calculated for fβ-hCG and PAPP-A and compared to the observed MoM (calculated by the Fetal Medicine Foundation screening algorithm).
  
  
  RESULTS
  fβ-hCG correlates positively with dCRL and negatively with dNT, whereas PAPP-A shows a positive correlation with dNT and a negative one with dCRL and dFHR. After adjustment for the ultrasound parameters, the median MoM values for fβ-hCG and PAPP-A changed from 1.02 and 0.92 observed MoM to 0.98 and 0.99 adjusted MoM respectively. The difference between the observed and adjusted MoM was statistically significant (p < 0.001). Delta CRL increases with gestation and this effect manifests mainly after CRL of 62 mm.
  
  
  CONCLUSIONS
  Adjustment for dCRL, dFHR and dNT improves the calculation of MoM for fβ-hCG and PAPP-A. CRL measurement overestimates fetal size at the end of the screening period 11-14 weeks.
authors: Fetal Medicine Unit, 3rd Department of Obstetrics and Gynaecology, University of Athens, Attikon University Hospital, Athens, Greece.
authors: Ioannis
authors: I
authors: Papastefanou
authors: Athena
authors: A
authors: Souka
authors: Makarios
authors: M
authors: Eleuftheriades
authors: Athanasios
authors: A
authors: Pilalis
authors: Demetrios
authors: D
authors: Kassanos
mesh_terms: D000293:Adolescent; D000328:Adult; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood*; D003430:Cross-Sectional Studies; D005260:Female; D006340:Heart Rate, Fetal; D006801:Humans; D048208:Nuchal Translucency Measurement; D011247:Pregnancy / Q000097:blood*; D011261:Pregnancy Trimester, First; D011266:Pregnancy-Associated Plasma Protein-A / Q000378:metabolism*; D012189:Retrospective Studies; D055815:Young Adult
chemical_list: D018997:Chorionic Gonadotropin, beta Subunit, Human; D011266:Pregnancy-Associated Plasma Protein-A