Screening all pregnant women by culture for rectovaginal group B streptococcus (GBS) colonization at 35 to 37 weeks' gestation lowers the annual incidence of early-onset GBS disease (occurring in infants aged 0–6 days of age), according to a recent CDC report.
In fact, the incidence dropped 33% during 2003–2005, shortly after universal screening guidelines were published, when compared with 2000–2001, before the guidelines came out. But while the incidence among white infants decreased steadily during the period 2003–2005, the incidence among black infants increased 70%. And universal screening seems to have had no effect on the incidence of late-onset disease (in infants 7–89 days of age) or the incidence in pregnant women, both of which remained steady after universal screening began.
Centers for Disease Control and Prevention (CDC). Perinatal group B streptococcal disease after universal screening recommendations-United States, 2003–2005. MMWR Morb Mortal Wkly Rep. 2007;56(28):701-705.