TUESDAY, Dec. 6 (HealthDay News) -- Giving steroids to pregnant women at risk for preterm birth as early as 23 weeks during their pregnancy may boost an infant's overall chance of survival and reduce the baby's risk of serious developmental issues, including brain injury, a new study says.

The study, published in the Dec. 7 issue of the Journal of the American Medical Association, is potentially significant, according to experts who are not affiliated with the study.

Current guidelines suggest administering prenatal steroids to women who are at risk for delivering between the 24th and 34th week of their pregnancy, but make no recommendations about what to do if women show signs of labor before week 24. Most "full-term" babies are born between 38 and 42 weeks. Steroids help the infants' lungs develop and this increases survival rates and lowers their risk of brain injury.

The new study provides some much-needed clarity for mothers and doctors of babies who are born at 23 weeks.

"When given as early as 23 weeks, prenatal or antenatal steroids reduce an infant's risk of death and important developmental issues," said study author Dr. Wally Carlo, director of the division of neonatology at the University of Alabama at Birmingham.

In the absence of clear guidelines, standard practice varies widely, he said. In the study, around 40 percent of women who showed signs of preterm labor at 23 weeks were not treated with steroids. "There is a huge potential to increase the use of prenatal steroids," he said. "Mothers need to know that there is a lot that physicians can do to improve the outcome for these babies."

The new study included about 10,500 infants born at 23 medical centers between January 1993 and January 2008 at 22 to 25 weeks. These babies weighed shy of 2 pounds at birth. The study compared infants who received prenatal steroids to those who had not. The researchers also performed neurologic exams on more than 4,900 of the surviving infants at 18 to 22 months after their original due dates.

When steroids were given to moms during their 22nd to 23rd week of pregnancy, infants' risk of death decreased by more than 33 percent, and their risk of neurodevelopmental delays dropped by more than 20 percent, the study showed. Such neurodevelopmental delays may include blindness, hearing impairment, cerebral palsy or severe delays in motor and cognitive issues. The treatment worked across many subgroups of women, Carlo said. "Even one dose may have important effects," he noted.

This suggests that prenatal steroids work just as well in babies born at 23 weeks as they do in those born at 26 weeks.

Dr. Burton Rochelson, chief of maternal-fetal medicine at the North Shore-Long Island Jewish Health System in Great Neck, N.Y., called the new study findings "important" and "a big deal." This study "provides pretty convincing evidence that we can give these steroids to infants between 22 and 23 weeks of pregnancy," he said. "If it looks like you are going to deliver even as early as 23 weeks, you should have a discussion with your doctor and be offered corticosteroids."

More information

Visit the March of Dimes to learn more about preterm birth.