Group B streptococcus (GBS) or Streptococcus agalactiae is a β-hemolytic, Gram-positive bacterium that is a leading cause of neonatal infections. GBS commonly colonizes the lower gastrointestinal and genital tracts and, during pregnancy, neonates are at risk of infection. Although intrapartum antibiotic prophylaxis during labor and delivery has decreased the incidence of early-onset neonatal infection, these measures do not prevent ascending infection that can occur earlier in pregnancy leading to preterm births, stillbirths, or late-onset neonatal infections. Prevention of GBS infection in pregnancy is complex and is likely influenced by multiple factors, including pathogenicity, host factors, vaginal microbiome, false-negative screening, and/or changes in antibiotic resistance. A deeper understanding of the mechanisms of GBS infections during pregnancy will facilitate the development of novel therapeutics and vaccines. Here, we summarize and discuss important advancements in our understanding of GBS vaginal colonization, ascending infection, and preterm birth.

B组链球菌（GBS）或无乳链球菌是一种β-溶血性革兰氏阳性细菌，是新生儿感染的主要原因。GBS通常定植在下消化道和生殖道，并且在怀孕期间，新生儿有感染的风险。尽管在分娩和生产过程中进行产前抗生素预防已降低了早发型新生儿感染的发生率，但这些措施并不能防止在孕妇早期发生的上升感染，从而导致早产，死产或晚发型新生儿感染。妊娠期GBS感染的预防很复杂，可能受多种因素影响，包括致病性，宿主因素，阴道微生物组，假阴性筛查和/或抗生素耐药性变化。怀孕期间对GBS感染机制的更深入了解将促进新型疗法和疫苗的开发。在这里，我们总结并讨论了我们对GBS阴道定植，上升感染和早产的重要进展。