title: Reference standard for serum bile acids in pregnancy.
abstract: OBJECTIVE
  Obstetric cholestasis (OC) is a liver disorder characterised by pruritus and elevated serum bile acids (SBA) that affects one in 200 pregnant women. It is associated with adverse perinatal outcomes such as premature delivery and stillbirth. Mild OC is defined as SBA levels of 10-39 μmol/l, and severe OC is defined by levels >40 μmol/l. SBA levels in normal pregnancy have not been investigated. We aimed to establish reference values for SBA in healthy pregnant women across different trimesters of pregnancy.
  
  
  METHODS
  Cross-sectional analysis of SBA levels.
  
  
  METHODS
  A large tertiary referral university teaching maternity hospital.
  
  
  METHODS
  Healthy pregnant women with a singleton pregnancy and a body mass index (BMI) < 40, excluding women with significant alcohol intake, history of liver disease, prior cholecystectomy and OC.
  
  
  METHODS
  Cross-sectional analysis of SBA levels at 12, 20, 28 and 36 weeks of gestation, and on days 1-3 postpartum.
  
  
  METHODS
  SBA levels in μmol/l.
  
  
  RESULTS
  A total of 219 women attending for antenatal care were recruited, and SBA levels were assayed at 12, 20, 28 and 36 weeks of gestation, and up to 72 hours postpartum (n = 44-49 cases at each stage). The majority were white European women, with a median age of 30 years (range 17-46 years) and median BMI of 25 (range 18-38). Values of SBA ranged from 0.3 to 9.8 μmol/l in 216 women, with only three measurements outside this range. There were no significant changes throughout pregnancy.
  
  
  CONCLUSIONS
  SBA values in uncomplicated pregnancies are consistent, regardless of gestation, and are not elevated in pregnancy. The current reference values for the diagnosis of OC appear to be appropriate.
authors.affiliation: Anu Research Centre, Department of Obstetrics and Gynaecology, University College Cork, Cork University Maternity Hospital, Cork, Ireland.
authors.forename: N
authors.initials: N
authors.lastname: Egan
authors.forename: A
authors.initials: A
authors.lastname: Bartels
authors.forename: A S
authors.initials: AS
authors.lastname: Khashan
authors.forename: D I
authors.initials: DI
authors.lastname: Broadhurst
authors.forename: C
authors.initials: C
authors.lastname: Joyce
authors.forename: J
authors.initials: J
authors.lastname: O'Mullane
authors.forename: K
authors.initials: K
authors.lastname: O'Donoghue
mesh_terms: D000293:Adolescent; D000328:Adult; D001647:Bile Acids and Salts / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D002779:Cholestasis / Q000097:blood*; D003430:Cross-Sectional Studies; D005260:Female; D005765:Gastrointestinal Agents / Q000097:blood*; D006771:Hospitals, Maternity; D006785:Hospitals, University; D006801:Humans; D008875:Middle Aged; D011247:Pregnancy; D011248:Pregnancy Complications / Q000097:blood*; D011256:Pregnancy Outcome; D011264:Pregnancy Trimesters; D011295:Prenatal Care / Q000379:methods; D012015:Reference Standards; D012307:Risk Factors; D012494:Sampling Studies
chemical_list: D001647:Bile Acids and Salts; D015415:Biomarkers; D005765:Gastrointestinal Agents