This volume focuses on microbiology and habitat of group B streptococci (GBS) along with GBS pathogenicity in neonates and adults. It highlights the role GBS may play as a cause for maternal morbidity and mortality and the relationship between vaginal colonization and neonate infection. The importance of GBS as a cause of newborn death or disability, miscarriage and stillbirth is emphasized, and the role of intrapartum antibiotic prophylaxis in reducing vertical transmission of this organism is underlined. In conclusion, microbiology may support a safe delivery and contribute to make the visit from the stork a happy event.