Increasing prevalence of group B streptococcal infection among pregnant women.

INTRODUCTION Group B streptococci (GBS) can cause preterm delivery for women and sepsis and meningitis in infants younger than 90 days of age. The present retrospective cohort study determines the trend over time in the rates of GBS and in demographic risk factors for GBS among pregnant women delivering at Rigshospitalet (RH). MATERIAL AND METHODS In the period from 2002 to 2010, a total of 33,616 women gave birth at the RH. Our cohort was defined as 16,587 (49%) women examined by 24,724 cultures. All microbiological requisitions from the Department of Obstetrics at RH were extracted from the Clinical Microbiology Database. Maternal data were obtained from a local database at the RH. RESULTS In our cohort, a total of 638 (3.8%) women were diagnosed with GBS, 517 (81%) from urine, 92 (14%) from vaginal swabs and 29 (5%) from both. The overall rate of women colonised with GBS rose from 3.3% in 2002 to 5.1% in 2010 (p < 0.0001). A total of 48 infants had early-onset group B streptococcus (EOGBS), 1.4 per 1,000 neonates in the general population and 7.8 per 1,000 among women with GBS (p < 0.0001). CONCLUSION We found a low GBS colonisation rate in our pregnant cohort, but the rate followed an increasing trend over the study period. GBS during pregnancy was associated with a low birth weight and preterm delivery. More research on preventive measures is needed, but updated guidelines, screening and intrapartum antibiotic prophylaxis continue to be the cornerstones of EOGBS disease prevention. FUNDING not relevant. TRIAL REGISTRATION not relevant.