2Stoll B J, Hansen N, Fanaroff AA, et al. Changes in pathogens causing early-onset sepsis in very-low-birth-weight infants [J]. N Engl J Med, 2002, 347 (4): 240-247.
3Yancey MK, Duff P, Clark P, et al. Peripartum infection associ- ated with vaginal group B streptococcal colonization [J]. Obstet Gynecol, 1994, 84 (5): 816-819.