WASHINGTON (AFP) - Babies born as early as 23 weeks showed better survival rates and less brain damage if their mothers were given steroids in the days preceding their birth, a US study said Tuesday. The research in the December 7 issue of the Journal of the American Medical Association suggests that preterm babies may benefit sooner than thought from the boost in lung power and organ growth they get from exposure to steroids. Until now, little was known about the efficacy of giving a pregnant woman steroids for a fetus less than 24 weeks old, and some were worried it could raise the risk of infection in the mother. Current guidelines, published in 1995, recommend a two-shot regimen for mothers who go into preterm labor when the fetus is between 24 and 34 weeks of age. A normal full-term pregnancy is between 37 and 42 weeks. However, even though premature babies exposed to steroids were twice as likely to survive as those who were not, the researchers cautioned that overall survival still remained relatively low, at 36 percent. To determine if steroids could help the youngest babies survive after being born on the edge of viability, doctor Waldemar Carlo of the University of Alabama at Birmingham and colleagues looked back at records between 1993 and 2009 at 23 academic perinatal centers in the United States. Data included babies born between 401 grams (14.1 ounces) and 1,000 grams (35.3 ounces) at 22 to 25 weeks gestation. Among babies born at 23 weeks who were exposed to steroids, 83 percent either died or had brain development problems by age 18-22 months. Ninety percent of those who werent given steroids either died or showed brain damage. The same advantages were not seen at a statistically significant level in babies aged 22 weeks who were exposed to steroids.