title: First-trimester reference ranges for decidual thickness and its relation to progesterone levels.
abstract: OBJECTIVE
  The present study aimed to provide normal reference ranges for decidual thickness measured ultrasonographically in healthy first-trimester pregnancies and to evaluate whether there was a relationship between decidual thickness and serum progesterone levels.
  
  
  METHODS
  Decidual thickness of 173 women with a healthy gestation between 6+0 and 9+6 weeks was measured ultrasonographically and serum progesterone concentration was determined. Distribution of decidual thickness at each gestational week and its relation with serum progesterone levels was evaluated.
  
  
  RESULTS
  Mean decidual thickness was 6.8, 5.7, 5.5, and 6.1 mm at 6th, 7th, 8th, and 9th gestational weeks, respectively. Decidual thickness showed a mild negative correlation with gestational week (ρ=-0.207, P=0.006) and a mild positive correlation with serum progesterone concentrations (ρ=0.191, P=0.021).
  
  
  CONCLUSIONS
  The present study provided normal reference ranges for decidual thickness in healthy pregnancies in the first trimester. The association found between decidual thickness and progesterone levels might shed light on further studies investigating the predictive factors of pregnancy loss and might lead to changes in the management of threatened miscarriage.
authors.affiliation: Department of Obstetrics and Gynecology, Fatih University, Faculty of Medicine, Ankara, Turkey. denizhizli@yahoo.com
authors.forename: Deniz
authors.initials: D
authors.lastname: Hızlı
authors.forename: Nermin
authors.initials: N
authors.lastname: Köşüş
authors.forename: Aydin
authors.initials: A
authors.lastname: Köşüş
authors.forename: Burcu
authors.initials: B
authors.lastname: Kasap
authors.forename: Hasan
authors.initials: H
authors.lastname: Kafali
authors.forename: Nilgün Ö
authors.initials: NÖ
authors.lastname: Turhan
mesh_terms: D000328:Adult; D003656:Decidua / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D011247:Pregnancy / Q000097:blood*; D011261:Pregnancy Trimester, First; D011374:Progesterone / Q000097:blood*; D012016:Reference Values; D014421:Turkey; D014463:Ultrasonography; D055815:Young Adult
chemical_list: D011374:Progesterone