Early Onset Group B Streptococcal Morbidity in Sweden : Analysis of a Population-Based Cohort. Stellan Håkansson, Department of Pediatrics/Neonatology, University Hospital, SE Umeå, Sweden Karin Källén, Department of Reproductive Epidemiology, Tornblad Institute, Lund University, SE , Lund, Sweden BACKGROUND / AIM: The impact of early onset group B streptococcal (EOGBS) sepsis in infants usually refers to the number of cases with positive cultures from blood and/or spinal fluid. To estimate the total burden of EOGBS morbidity cases with clinical sepsis and pneumonia should also be taken into account. The objective of the present study was to assess the total EOGBS morbidity in Sweden, and to analyze associated risk factors relating to pregnancy and delivery. METHOD: For the period data were retrieved from the Medical Birth Registry, the Hospital Discharge Registry, and the Causes of Death Registry. Infants with the ICD-10 diagnoses GBS sepsis (P36.0) and/or GBS pneumonia (P23.3) were analyzed. In infants with P36.0, the register data were validated against maternal medical records from the delivery and the infant's discharge synopsis. Out of 372 cases with P36.0, 31 infant records were missing and 21 cases were late onset. In 320 infants with diagnosis P36.0 the medical records were available, and of these, 305 also with maternal records. There were 212 cases with pneumonia, 180 of which did not have a sepsis diagnosis. During the study period the total number of live births was 435,070. Risk estimates (OR and 95% CI) for tentative background risk factors were analyzed in three categories of EOGBS disease: 1) verified sepsis, 2) verified and clinical sepsis, and 3) verified and clinical sepsis and pneumonia. RESULTS a) : 319 cases with early onset sepsis were retrieved from register data and one case was added after the request for medical records from the NICUs. Blood culture verified 174 cases, including 6 infants with meningitis. In 146 cases blood culture was negative and therefore classified as clinical sepsis, by presence of all of the following: surface GBS colonization, CRP level  25 mg/L, and relevant signs and symptoms in the infants. The incidences of cases with verified sepsis, clinical sepsis, and pneumonia without sepsis were 0.40, 0.34, and 0.41 per 1000 live births. The mortality in respective diagnosis category was 6.9, 0.7, and 1.7%. In cases with verified sepsis the mortality among preterm (n=56) and term infants (n=118) was 17.8% and 1.7% respectively. During the 5 year period there was no trend towards decreasing EOGBS morbidity. In infants with verified or clinical sepsis the proportions of maternal risk factors were: <37 W GA = 27%; Temp  38 o C = 22%; ROM  18h = 44%. In 187 (61 %) of the parturients at least one risk factor was present. Of these, 20 (11 %) had received intrapartum antibiotic prophylaxis (IAP) more than 2 hours before delivery. a) Preliminary figures in abstract slightly amended. CONCLUSIONS: The total burden of EOGBS morbidity was approximately 3 times higher than the incidence of blood culture proven GBS sepsis. The data confirm the very high risk for preterm infants. Term delivery at 37 W, postmaturity, epidural anesthesia, gestational diabetes, primiparity, male gender and a LGA infant also add to the risk for EOGBS disease. Multiparity was not an independent risk factor, nor was maternal smoking or a SGA infant. Although the incidence and case/fatality rate were relatively low, a more elaborate use of IAP could probably further reduce EOGBS morbidity and mortality in Sweden. 22.1( )11.1( )12.4 ( ) 35.9 ( )19.4( )14.7( ) 12.4 ( )8.4( ) 5.8( ) 4.3( )3.6( ) 3.1( ) 3.4( )2.2( ) 1.9( ) 1.8( )1.7( ) 1.7 ( ) 1.3( )1.3( ) 1.1( ) 1.1( )1.5( ) 1.3( ) 1.3( )1.4( ) 1.4( ) 3.0( )2.4 ( ) 2.3( ) 0.5( )0.5( ) 0.5 ( ) 0.8( )0.7 ( ) 0.7 ( ) 1.5( )1.8 ( ) 1.8( ) ( ) 0.8( )1.1( ) 1.0( ) 0.7( )0.7( ) 0.7( ) 3.2( )2.6( ) 2.1( ) Tentative risk factor / Reference Verified sepsis n=174 Verified sepsis & Clinical sepsis n=319 ( ) Verified sepsis & Clinical sepsis & Pneumonia n=499 ( ) Risk Factors for EOGBS Disease OR (95% Confidence Interval) Adjustments were made for year of birth, maternal age, parity, smoking, gestational age, and birth weight when relevant. Figures in red denote statistical significance, the confidence interval not including 1.0. <28W / 40W W / 40W 34-32W / 40W 36-35W / 40W 37W / 40W  42W / 40W Maternal age <20 Y / Y Maternal age  42 Y / Y Epidural analgesia / No EDA (vaginal delivery) Gestational diabetes / No gest diab Parity  2 / Parity =1 Female / Male infant Large for gestational age / Adequate for GA Small for gestational age / Adequate for GA Maternal smoking / No maternal smoking Twin / Singelton (adjusted for GA) Twin / Singelton (not adjusted for GA) Gestational age