Objective. To evaluate the costs and benefits of a group B streptococci screening strategy using a new, rapid polymerase chain reaction test in a hypothetical cohort of expectant mothers in the United States.

Methods. Design. Cost-benefit analysis using the human capital method. We developed a decision model to analyze the costs and benefits of a hypothetical group B streptococci screening strategy using a new, rapid polymerase chain reaction test as compared with the currently recommended group B streptococci screening guidelines-prenatal culture performed at 35 to 37 weeks or risk-factorbased strategy with subsequent intrapartum treatment of the expectant mothers with antibiotics to prevent early-onset group B streptococcal infections in their infants.

Participants. A hypothetical cohort of pregnant women and their newborns.

Interventions. Screening strategies for group B streptococci using the new polymerase chain reaction technique, the 35- to 37-week culture, or maternal risk factors.

Outcome Measures. Infant infections averted, infant deaths, infant disabilities, costs, and societal benefits of healthy infants.

Results. A screening strategy using the new polymerase chain reaction test generates a net benefit of $7 per birth when compared with the maternal risk-factor strategy. For every 1 million births, 80 700 more women would receive antibiotics, 884 fewer infants would become infected with early-onset group B streptococci, and 23 infants would be saved from death or disability. The polymerase chain reaction-based strategy generates a net benefit of $6 per birth when compared with the 35- to 37-week prenatal culture strategy and results in fewer maternal courses of antibiotics (64 080 per million births), fewer perinatal infections with early-onset group B streptococci (218/million), and a reduction in 6 infant deaths and severe infant disability per million births. The benefits hold over a wide range of assumptions regarding key factors in the analysis.

Conclusions. Although additional clinical trials are needed to establish the accuracy of this new polymerase chain reaction test, initial studies suggest that strategies using this test will be superior to the other 2 strategies. Using the rapid polymerase chain reaction test becomes less attractive as the cost of the test increases. The test's greatest strengths lie in its ability to identify women and infants at risk at the time of labor, thereby decreasing the number of false-positives and false-negatives seen with the other 2 strategies and allowing for more accurate and effective intrapartum prophylaxis.