NEW YORK (Reuters Health) - There has been a marked increase in screening pregnant women to see if they're carrying group B streptococcus (GBS), ever since national guidelines began recommending universal screening late in pregnancy, new research shows.

GBS can be passed from the mother to the baby during delivery. It is the most common cause of blood infection and meningitis in newborns and is a frequent cause of newborn pneumonia. Between 10 and 20 percent of infected infants die, and many of the survivors have permanent brain damage.

The lead investigator on the present study, Dr. Melissa K. Van Dyke, from the Centers for Disease Control and Prevention, Atlanta, told Reuters Health, "This is the first multi-state, population-based evaluation of the universal antenatal GBS screening recommendations issued in 2002." The results indicate that "universal screening was rapidly adopted after recommendations."

Screening increased from 48 percent in 1998-1999 to 85 percent in 2003-2004, according to the report in this week's New England Journal of Medicine.

Eighty-seven percent of women who tested positive for GBS who delivered at term received preventative antibiotics.

Overall, the rate of early-onset GBS disease was 0.32 cases per 1000 live births. Preterm infants had a higher rate of early-onset disease than did term infants, although almost three-quarters of cases occurred in term infants.

The take-home message is that "pregnant women should be screened at 35-37 weeks gestation, and culture-positive women should receive intrapartum antibiotic prophylaxis," Van Dyke said. "Antenatal screening is the best strategy for prevention of early-onset GBS disease, but the CDC is working to see how recommendations could be improved."

SOURCE: New England Journal of Medicine, June 18, 2009.