The effectiveness of risk-based intrapartum chemoprophylaxis for the prevention of early-onset neonatal group B streptococcal disease

Am J Obstet Gynecol. 2001 May;184(6):1204-10. doi: 10.1067/mob.2001.113875.


Objective: Our purpose was to evaluate the effectiveness of a risk-based intrapartum antibiotic prophylaxis strategy for the prevention of early-onset neonatal group B streptococcal disease.

Study design: Cases and controls were selected from infants born to women with one or more risk factors: preterm labor or rupture of membranes, prolonged rupture of membranes (>18 hours), fever during labor, or previous child with group B streptococcal disease. Cases were matched with controls by birth hospital and gestational age. Data abstracted from medical records were analyzed to estimate the effectiveness of intrapartum antibiotic prophylaxis.

Results: We analyzed data from 109 cases and 207 controls. Nineteen (17%) case versus 69 (33%) control mothers received an acceptable regimen of intrapartum antibiotic prophylaxis. In adjusted analyses, the effectiveness of intrapartum antibiotic prophylaxis was 86% (95% confidence interval, 66%-94%). When the first dose of antibiotics was given > or =2 hours before delivery, the effectiveness increased to 89% (95% confidence interval, 70%-96%); when it was given within 2 hours of delivery, the effectiveness was 71% (95% confidence interval, -8%-92%). Effectiveness was lowest in mothers with intrapartum fever (72%, 95% confidence interval, -9%-93%). On the basis of a 70% prevalence of maternal risk factors expected among cases in the absence of intrapartum antibiotic prophylaxis, we estimate that the risk-based strategy could reduce early-onset group B streptococcal disease by 60%.

Conclusions: The risk-based approach to intrapartum antibiotic prophylaxis is effective in preventing early-onset group B streptococcal disease. To achieve the maximum preventive effect, the first dose of antibiotics should be administered at least 2 hours before delivery.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Anti-Bacterial Agents / administration & dosage
  • Antibiotic Prophylaxis*
  • Case-Control Studies
  • Drug Administration Schedule
  • Female
  • Humans
  • Infant, Newborn
  • Labor, Obstetric*
  • Male
  • Pregnancy
  • Risk Factors
  • Streptococcal Infections / prevention & control*
  • Streptococcus agalactiae*
  • Treatment Outcome


  • Anti-Bacterial Agents