ObjectiveTo evaluate hospital-based practices for perinatal group B streptococcal disease prevention and to identify institutional factors related to the disease.MethodsWe surveyed microbiology laboratories and obstetric programs during 1994 at hospitals in five states with active surveillance for invasive group B streptococcal disease. Institutions provided information on methods for detecting carriers and on obstetric policies for group B streptococcal disease prevention. We used linear regression to identify prevention practices and hospital characteristics that correlated with the number of cases of early-onset disease.ResultsOf 295 hospitals, 247 (84%) laboratories and 154 (52%) obstetric programs completed the survey. Most (83%) laboratories performed group B streptococcal cultures on rectal and vaginal specimens, but only 12 (6%) used selective broth media. Among the obstetric programs, 54 (35%) had policies on some aspect of group B streptococcal disease prevention. Of the hospitals with policies, 21 (48%) recommended intrapartum antimicrobial prophylaxis for women with risk factors outlined by the 1992 ACOG statement. Adjusting for the number of births, there were more cases of early-onset group B streptococcal disease in institutions providing care for more African American women and for more women with no prenatal care. Institutions that had group B streptococcal screening policies had fewer early-onset cases.ConclusionMany institutions with prevention policies followed practices that differed from those recommended in published prevention statements. Having any screening policy, however, was associated with reduced early-onset disease, independent of the risk profile of the patient population. Adopting prevention policies is most urgent for practices serving individuals at increased risk, such as African American women and women without prenatal care.