title: The plasma levels of the endocannabinoid, anandamide, increase with the induction of labour.
abstract: OBJECTIVE
  Plasma anandamide (AEA) levels have previously been shown to be elevated in labour and defective cannabinoid receptor type 1 signalling in mice has been shown to be associated with elevation of corticotrophin-releasing hormone and spontaneous onset of preterm labour. We measured plasma AEA levels in women undergoing induction of labour to define the changes during the transition from the nonlabouring to labouring state.
  
  
  METHODS
  A longitudinal observational study.
  
  
  METHODS
  A large UK teaching hospital.
  
  
  METHODS
  Term pregnant women undergoing induction of labour.
  
  
  METHODS
  Blood was collected from women before induction of labour and again when they were in active labour. Plasma AEA was extracted and measured using ultraperformance liquid chromatography-tandem mass spectrometry.
  
  
  METHODS
  The primary outcome variable was change in plasma AEA levels from the nonlabouring to the labouring state. The secondary outcome was induction-to-delivery interval.
  
  
  RESULTS
  There was a 1.5-fold increase in mean plasma AEA levels from 1.20 +/- 0.57 nm in the nonlabouring state to 1.82 +/- 0.87 nm in the labouring state (P < 0.0001). Induction-to-delivery interval was predicted by both Bishop's score (P < 0.0001) and percentage change in plasma AEA levels (P < 0.0001). There was a negative correlation between the percentage change in plasma AEA level and the induction-to-delivery interval (r = - 0.28; P = 0.0481). This means that the greater the rise in the plasma AEA levels the shorter the duration of labour.
  
  
  CONCLUSIONS
  Plasma AEA levels increase with active labour and the negative correlations between percentage change in plasma AEA levels and induction-to-delivery interval suggest that AEA is likely to be involved in the physiological mechanisms of labour. Whether this increase is essential for myometrial contraction is unclear and needs further investigation.
authors.affiliation: Endocannabinoid Research Group, Reproductive Sciences Section, Department of Cancer Studies and Molecular Medicine, University of Leicester, Leicester Royal Infirmary, Leicester, UK.
authors.forename: V
authors.initials: V
authors.lastname: Nallendran
authors.forename: P M W
authors.initials: PM
authors.lastname: Lam
authors.forename: T H
authors.initials: TH
authors.lastname: Marczylo
authors.forename: M J G
authors.initials: MJ
authors.lastname: Bankart
authors.forename: A H
authors.initials: AH
authors.lastname: Taylor
authors.forename: D J
authors.initials: DJ
authors.lastname: Taylor
authors.forename: J C
authors.initials: JC
authors.lastname: Konje
mesh_terms: D000293:Adolescent; D000328:Adult; D001095:Arachidonic Acids / Q000097:blood*; D063385:Cannabinoid Receptor Modulators / Q000097:blood*; D002853:Chromatography, Liquid; D063388:Endocannabinoids; D005260:Female; D006801:Humans; D007751:Labor, Induced; D007743:Labor, Obstetric / Q000097:blood*; D053284:Polyunsaturated Alkamides / Q000097:blood*; D011247:Pregnancy; D055815:Young Adult
chemical_list: D001095:Arachidonic Acids; D063385:Cannabinoid Receptor Modulators; D063388:Endocannabinoids; D053284:Polyunsaturated Alkamides; C078814:anandamide