title: Correlation of 2nd trimester amniotic fluid amino acid profile with gestational age and estimated fetal weight.
abstract: OBJECTIVE
  Our aim was to identify and quantitate free amino acids in human amniotic fluid (AF) specimens collected during 2nd trimester amniocentesis and determine the correlation between amino acid concentrations, gestational age, and estimated fetal weight.
  
  
  METHODS
  Seventy-eight AF samples were retrieved between 18 and 22 weeks of gestation. Fetal weight estimation was based on fetal biometric measurements.
  
  
  RESULTS
  Twenty-one amino acids were quantified. The concentration of glutamine exhibited the greatest correlation with gestational age (r = 0.477, p < 0.01). Additionally, significant negative correlations were recorded between gestational age and levels of alanine, proline, lysine, valine, taurine, leucine, glutamic acid, tyrosine, phenylalanine, isoleucine, ornithine, methionine, and tryptophane (p < 0.05). After adjusting for maternal age, fetal gender, intervals between consecutive pregnancies, pre-pregnancy body mass index, and smoking during pregnancy the strength of the correlation for proline and lysine decreased. A stepwise multiple linear regression model including gestational age as a first level predictor of fetal weight indicated that lysine and cysteine concentrations were additional predictors.
  
  
  CONCLUSIONS
  Our results suggest that AF amino acids are crucial for fetal growth. Our purpose was not to establish an immediate diagnostic application. However, further exploration is likely to be fruitful, especially in high-risk pregnancies.
authors.affiliation: 1st Department of Obstetrics & Gynecology, Medical School, Aristotle University of Thessaloniki, Thessaloniki, Greece. apostolos3435@gmail.com
authors.forename: Apostolos P
authors.initials: AP
authors.lastname: Athanasiadis
authors.forename: Alexandra-Maria
authors.initials: AM
authors.lastname: Michaelidou
authors.forename: Maria
authors.initials: M
authors.lastname: Fotiou
authors.forename: George
authors.initials: G
authors.lastname: Menexes
authors.forename: Theodoros D
authors.initials: TD
authors.lastname: Theodoridis
authors.forename: Maria
authors.initials: M
authors.lastname: Ganidou
authors.forename: Basilis
authors.initials: B
authors.lastname: Tzevelekis
authors.forename: Efstratios
authors.initials: E
authors.lastname: Assimakopoulos
authors.forename: Basil C
authors.initials: BC
authors.lastname: Tarlatzis
mesh_terms: D000328:Adult; D000596:Amino Acids / Q000032:analysis*; D000649:Amniocentesis; D000653:Amniotic Fluid / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D005260:Female; D020567:Fetal Weight; D005865:Gestational Age; D006801:Humans; D016014:Linear Models; D011247:Pregnancy; D011262:Pregnancy Trimester, Second
chemical_list: D000596:Amino Acids