A Retrospective Study Comparing of Group B Streptococcus Invasiveness in Pregnant Women and Infants

Background: Group B streptococcus (GBS) is commonly recognized as an opportunistic pathogen, which can cause infections in pregnant women and their newborns. The aim of this study was to explore the invasiveness of GBS by comparing various indices of pregnant mothers and newborns. Methods: This retrospective study involved 6892 consecutive GBS screened pregnant women, and 48 GBS-positive newborns. The data of pregnant women and newborns was compared by Chi-square test and Kruskal-Wallis test. A p-value ≤ 0.05 was considered statistically significant. Results: After excluding the other risk factors which can cause adverse pregnancy outcomes, there were no differences between pregnant women in GBS-positive and GBS-negative groups, except the age group. In the GBS-negative and positive groups the incidence of prematurity, premature rupture of membranes (PROM), and chorioamnionitis were 1.06% and 0.74%, 7.72% and 8.14%, 0.63% and 0.74%, respectively. The corresponding p-values were 0.619, 0.263, and 0.626. The GBS-positive rate was 6.83% (201/2943) in the 19–30 years (y) group, 6.89% in the (262/3802) in the 31–40 y group, and 1.36% (2/147) in the 41–52 y group (p = 0.031). The indices in the different newborn groups exhibited significant differences. Analysis of the data revealed significant differences in delivery mode, gestational age, neonatal birth weight, and Apgar scores among the GBS-colonization, GBS-infection, and death groups (p = 0.010, 0.004, 0.022, and 0.000 < 0.05, respectively). Conclusions: After excluding related factors, the evidence showing that GBS-colonization independently induced adverse pregnancy outcomes in pregnant women was insufficient. GBS was more likely to attack premature newborns with low weight and poor health status.