title: Outpatient calcium-channel blockers and the risk of postpartum haemorrhage: a cohort study.
abstract: OBJECTIVE
  To determine whether outpatient exposure to calcium-channel blockers (CCBs) at the time of delivery is associated with an increased risk for postpartum haemorrhage (PPH).
  
  
  METHODS
  Cohort study.
  
  
  METHODS
  United States of America.
  
  
  METHODS
  Medicaid beneficiaries.
  
  
  METHODS
  We identified a cohort of 9750 patients with outpatient prescriptions for CCBs, methyldopa, or labetalol for pre-existing or gestational hypertension whose days of supply overlapped with delivery; 1226 were exposed to CCBs. The risk of PPH was compared in those exposed to CCBs to those exposed to methyldopa or labetalol. Propensity score matching and stratification were used to address potential confounding.
  
  
  METHODS
  The occurrence of PPH during the delivery hospitalisation.
  
  
  RESULTS
  There were 27 patients exposed to CCBs (2.2%) and 232 patients exposed to methyldopa or labetalol (2.7%) who experienced PPH. After accounting for confounders, there was no meaningful association between CCB exposure and PPH in the propensity score matched (odds ratio 0.77, 95% CI 0.50-1.18) or stratified (odds ratio 0.79, 95% CI 0.53-1.19) analyses. Similar results were obtained across multiple sensitivity analyses.
  
  
  CONCLUSIONS
  The outpatient use of CCBs in late pregnancy for the treatment of hypertension does not increase the risk of PPH.
authors.affiliation: Division of Pharmacoepidemiology and Pharmacoeconomics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA; Department of Anesthesiology, Critical Care, and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: B T
authors.initials: BT
authors.lastname: Bateman
authors.forename: S
authors.initials: S
authors.lastname: Hernandez-Diaz
authors.forename: K F
authors.initials: KF
authors.lastname: Huybrechts
authors.forename: K
authors.initials: K
authors.lastname: Palmsten
authors.forename: H
authors.initials: H
authors.lastname: Mogun
authors.forename: J L
authors.initials: JL
authors.lastname: Ecker
authors.forename: E W
authors.initials: EW
authors.lastname: Seely
authors.forename: M A
authors.initials: MA
authors.lastname: Fischer
mesh_terms: D000293:Adolescent; D000328:Adult; D000959:Antihypertensive Agents / Q000627:therapeutic use; D002121:Calcium Channel Blockers / Q000627:therapeutic use*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D006973:Hypertension / Q000188:drug therapy*; D007741:Labetalol / Q000627:therapeutic use; D008484:Medicaid; D008750:Methyldopa / Q000627:therapeutic use; D006473:Postpartum Hemorrhage / Q000453:epidemiology*; D011247:Pregnancy; D057216:Propensity Score; D018570:Risk Assessment; D014481:United States; D014593:Uterine Inertia / Q000453:epidemiology; D055815:Young Adult
chemical_list: D000959:Antihypertensive Agents; D002121:Calcium Channel Blockers; D008750:Methyldopa; D007741:Labetalol
keywords: Calcium-channel blockers; hypertensive disorders of pregnancy; postpartum haemorrhage
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