title: Reference centile charts for ratio of fetal transverse cerebellar diameter to abdominal circumference in a Thai population.
abstract: OBJECTIVE
  To establish the centile chart for the ratio of transverse cerebeller diameter to abdominal circumference throughout pregnancy from 13-40 weeks.
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  Department of Maternal - Fetal Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University.
  
  
  METHODS
  The participants are women with gestational age between 13 and 40 weeks who attend Antenatal Clinic, Siriraj Hospital.
  
  
  METHODS
  A total of 643 pregnant women were recruited in this study. The exclusion criteria were uncertained date of last menstrual period, multiple pregnancies, fetal abnormalities and maternal conditions which could affect fetal growth. Transverse cerebellar diameter and abdominal circumference of all the subjects were measured out by gestational age. The approximately equal numbers of fetuses were measured at each week of gestation. The mean and standard deviation of TCD/AC ratio is estimated at each week of gestation. In addition the 5th, 10th, 50th, 90th and 95th percentiles were calculated at each week of gestation.
  
  
  RESULTS
  Of 643 pregnant women, 149 (23.1%) were scanned before 20 weeks of gestation and 286 (44.5%) were scanned between 20 and 30 weeks of gestation. The last group was intervened after 30 weeks of gestation. TCD/AC ratio slowly declined from early pregnancy until about 20 weeks then remained stable. After 30 weeks of gestation it started to decline again.
  
  
  CONCLUSIONS
  The normal reference value of TCD/AC ratio in Thai fetus were shown in this study. This ratio can be used to calculate gestational age in intrauterine growth restriction fetus.
authors.affiliation: Department of Obstetrics and Gynecology, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand.
authors.forename: Nitsana
authors.initials: N
authors.lastname: Singhakom
authors.forename: Saifon
authors.initials: S
authors.lastname: Chawanpaiboon
authors.forename: Vitaya
authors.initials: V
authors.lastname: Titapant
mesh_terms: D000886:Anthropometry; D044466:Asian People; D002508:Cephalometry / Q000379:methods*; D002531:Cerebellum / Q000000981:diagnostic imaging*; D003430:Cross-Sectional Studies; D005260:Female; D047109:Fetal Development / Q000502:physiology*; D005865:Gestational Age; D006801:Humans; D011247:Pregnancy; D011264:Pregnancy Trimesters; D012016:Reference Values; D013785:Thailand; D016216:Ultrasonography, Prenatal / Q000379:methods*