High maternal body mass index increases the risk of neonatal early onset group B streptococcal disease.

OBJECTIVE: The aim of this study was to analyse the occurrence of neonatal early onset group B streptococcal (EOGBS) disease relative to maternal body mass index (BMI).

METHOD: A cohort of Swedish parturients with an early pregnancy BMI registered was investigated. Data were retrieved from population-based registers during 1997-2001, (n = 344 127, elective caesarean section excluded). Medical records of all infants with a diagnosis of EOGBS septicaemia (P36.0) were scrutinized for verification of the diagnosis. There were 136 cases with blood culture-positive septicaemia and 112 cases with clinical infection. Odds ratios (OR) and 95% confidence intervals (CI) were calculated using multiple logistic regression.

RESULTS: In obese parturients with BMI > 30, there was an 80% increased risk for verified neonatal EOGBS disease (OR 1.8, 95% CI 1.1-3.0). When cases with clinical sepsis were included a significant risk increment was also found in overweight women with BMI 25.0-29.9 (OR 1.5, 95% CI 1.1-2.0).

CONCLUSION: Maternal obesity and overweight are risk factors associated with increased risk of neonatal EOGBS disease.