title: Cervical dilatation thresholds for initiation of group B streptococcus antibiotic prophylaxis for women with spontaneous preterm labor.
abstract: OBJECTIVE
  To determine the optimal time for initiating group B streptococcus (GBS) antibiotic prophylaxis for women in spontaneous preterm labor.
  
  
  METHODS
  In total, 227 women delivering singleton infants after presenting with spontaneous preterm labor and intact membranes at 24 0/7-36 6/7 weeks were evaluated, as well as 150 undelivered women with threatened preterm labor during the same time period. The date and time of each cervical examination throughout labor were recorded. We calculated the percentages who would have correctly received at least 4 h of GBS prophylaxis if antibiotics were routinely initiated for various cervical dilatation thresholds during labor, as well as the percentage of undelivered women who would have received unnecessary antibiotic exposure at each cervical dilatation cutoff.
  
  
  RESULTS
  Delaying antibiotics until cervical dilatation reached 2 cm or greater would have resulted in 62.1% receiving four or more hours of antibiotics, compared to 66.5% if antibiotics were started on all women at admission (p = 0.33), while significantly reducing unnecessary antibiotic exposure in undelivered women from 100% to 62.0% (p < 0.001). The 2-cm threshold was applicable regardless of gestational age period or prior vaginal delivery ≥ 20 weeks.
  
  
  CONCLUSIONS
  GBS antibiotic prophylaxis may reasonably be withheld for women with suspected preterm labor until the cervix reaches 2 cm or greater at any time during labor.
authors.affiliation: a Department of Obstetrics and Gynecology , University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School at Camden, Cooper University Hospital , Camden , NJ , USA .
authors.forename: Richard L
authors.initials: RL
authors.lastname: Fischer
authors.affiliation: b Robert Wood Johnson Medical School at Camden, University of Medicine and Dentistry of New Jersey , Camden , NJ , USA , and.
authors.forename: Laura
authors.initials: L
authors.lastname: Parikh
authors.affiliation: a Department of Obstetrics and Gynecology , University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School at Camden, Cooper University Hospital , Camden , NJ , USA .
authors.forename: Clare
authors.initials: C
authors.lastname: Hansen
authors.affiliation: c Cooper Research Institute, Cooper University Hospital , Camden , NJ , USA.
authors.forename: Krystal M
authors.initials: KM
authors.lastname: Hunter
mesh_terms: D000328:Adult; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D019072:Antibiotic Prophylaxis / Q000379:methods*; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D057970:Inappropriate Prescribing / Q000517:prevention & control* / Q000706:statistics & numerical data; D007747:Labor Stage, First; D007752:Obstetric Labor, Premature / Q000175:diagnosis / Q000188:drug therapy*; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000517:prevention & control*; D012189:Retrospective Studies; D013290:Streptococcal Infections / Q000517:prevention & control*; D013292:Streptococcus agalactiae
chemical_list: D000900:Anti-Bacterial Agents
keywords: Antibiotic prophylaxis; group B Streptococcus; preterm labor