Screening of group B Streptococcus infection in pregnancy and neonatal outcomes in the province of Trento, Italy

Abstract

The study analyzes the trend of group B streptococcal (GBS) infection in pregnancy in the province of Trento, Italy, where a universal screening of GBS infection in pregnancy has been active for some time. Data from pregnant women who gave birth at local maternity units between 2015-2019 were obtained from birth attendance certificates (BAC), the main - and mandatory - source of information for monitoring pregnancies, births and neonatal health in Italy. The BAC used in the province of Trento acquires the results of a vast range of infections in pregnancy. The data collected from the BAC were integrated with those provided by the Hospital Information System (SIO). The occurrence of neonatal GBS infection was investigated on 2019 birth cohort, using the hospital discharge archive as an ancillary information source. Between 2015-2019, 20,905 pregnant women received care at maternity units of the province of Trento, Italy, of whom 25.5% were foreigners. The average coverage of GBS testing in pregnancy was 91.8% (95% CI 91.25-92.35) without significant variations from one year to the next. Test coverage varies in relation to maternity units and some socio-demographic characteristics of mothers. The average proportion of GBS positive cases over the study period was 21.0% (95% CI 20.7-21.3), a value that does not show statistically significant changes from one year to the next. The proportion of positive cases appears uneven among the subgroups of pregnant women considered, even if the differences are not statistically significant. In the 2019 birth cohort, newborns to GBS-positive mothers had an excess of stillbirths, of those born with Apgar at 5 minutes <7 and hospitalized at birth. However, these excesses were not statistically significant. Intravenous Antibiotic Prophylaxis (IAP) was performed in 86.8% of births from GBS positive mothers who had an indication for IAP. IAP was inadequate in 7.4% of the GBS positive mothers. Postnatal evaluation of 783 live births to GBS positive mothers identified 3 cases of early neonatal GBS infection. The incidence of neonatal GBS infection over the whole series of live births is 0.71/1,000 (95% CI 0.56-0.86), 0.68/1000 (CI 95% 0.55-0.79) in Italians and 1.07/1000 (95% CI 0.45-1.65) in foreigners. Data collection on infections in pregnancy through BAC allows area-based assessment. The quality of the data recorded in the BAC can be considered satisfactory but it was necessary to access to other information sources. The local availability of various information sources should allow periodic audits and closer monitoring of neonatal GBS infection.

Keywords: Group B streptococcus infection; birth attendance certificate; neonatal infection; pregnancy; universal screening.