Impact and risk factors for early-onset group B streptococcal morbidity: analysis of a national, population-based cohort in Sweden 1997-2001

S Hakansson, Karin Källén

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Objectives To study early-onset group B streptococcal (EOGBS) morbidity, mortality, and maternal risk factors. Design Observational, population-based, retrospective. Data from national registers and medical records. Setting Sweden, 1997-2001. Population Cohort of 640 infants with a diagnosis of GBS infection out of 435 070 live births. Method Infants with diagnoses GBS sepsis (P36.0) and/or pneumonia (P23.3) were analysed. In cases with P36.0, register data were validated against infant and maternal medical records. Odds ratios (OR) were estimated by multiple logistic regression. Main outcome measures Incidence of EOGBS morbidity, mortality, frequency of maternal risk factors and administration of intrapartum antibiotics. Results There were 319 cases with EOGBS sepsis. Blood culture verified 174 cases. There were 145 with clinical sepsis and 180 with pneumonia only. The incidences were 0.40, 0.33, and 0.41 per 1000 live births, respectively. The mortality was 7.5, 0.7, and 2.2% in respective groups. The frequencies of established maternal risk factors were: membrane rupture >= 18 hours, 44%; prematurity, 26%; temperature during labour >= 38 degrees C, 22%. Novel maternal risk factors identified in verified cases were gestational age (GA) of 37 completed weeks (OR 3.5, 1.8-6.5) and gestational diabetes (OR 3.7, 1.8-8.5). When including clinical sepsis, also epidural anaesthesia, infant large for GA, postmaturity, and high maternal age were significant risk factors. Conclusion The incidence of verified EOGBS disease was 0.4 per 1000 live births with a total burden of EOGBS morbidity approximately three times higher. GA of 37 completed weeks and gestational diabetes were identified as additional significant risk factors.
Original languageEnglish
Pages (from-to)1452-1458
JournalBJOG: An International Journal of Obstetrics & Gynaecology
Issue number12
Publication statusPublished - 2006

Subject classification (UKÄ)

  • Obstetrics, Gynecology and Reproductive Medicine


  • infant
  • early onset
  • group B streptococcus
  • risk factors
  • intrapartum antibiotics


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