A new study from the University of Alabama at Birmingham suggests that women at risk of preterm delivery, from as early as 23 weeks of pregnancy, should receive corticosteroids due to strong associations with a lower rate of death and serious illness for their babies.

The study, published in the British Medical Journal, says that very premature babies seem to benefit the most from the steroids, even those born at 23 weeks of gestation.

“Indeed, the benefits of antenatal corticosteroids were substantially larger for infants born at the lowest gestations, including less than 28–week infants, for which data from randomized controlled trials are most limited,” said Wally Carlo, senior investigator of the study and director of the UAB Division of Neonatology.

Compared to babies born at term, premature babies carry a greater risk of death or serious complications after birth, with problems tending to be more severe the earlier a baby is born. Infants exposed to antenatal corticosteroids had lower mortality and lower rates of brain bleeding.

Colm Travers, MD, third–year fellow in the UAB Division of Neonatology, and a team of researchers analyzed data for 117,941 infants born between 23 and 34 weeks of gestation from 2009 to 2013 at 300 neonatal intensive care units across the United States. Death or major illness was analyzed by gestational age and exposure to antenatal corticosteroids, adjusting for factors such as birth weight, sex, mode of delivery and multiple births.

The researchers found that exposure to antenatal corticosteroids was associated with a significantly lower rate of death before discharge from hospital at each gestation compared with infants without exposure.

They also found that the number of infants needed to treat with antenatal corticosteroids to prevent one death before discharge increased from six at 23 and 24 weeks of gestation to 798 at 34 weeks of gestation, suggesting that infants born at the lowest gestational ages benefit most, even those born at 23 weeks.

The rate of survival without major illness while in hospital was also higher among infants exposed to antenatal corticosteroids at the lowest gestations.

“Among infants born from 23 to 34 weeks’ gestation, antenatal exposure to corticosteroids compared with no exposure was associated with lower mortality and morbidity at most gestations,” said Travers, principal investigator of the study. “This study highlights for the first time that infants at the lowest gestations seem to benefit the most from exposure to antenatal corticosteroids.”

The authors point out that this is an observational study, so no firm conclusions can be drawn about cause and effect, and they outline some limitations could have introduced bias.

Current guidelines recommend giving corticosteroids to at–risk women from 23 to 34 weeks of pregnancy. However, the benefits for lower mortality and morbidity for infants born at less than 28 weeks had been less clear.

“This study supports the administration of antenatal corticosteroids in women with threatened preterm labor from 23 to 34 weeks’ gestation, particularly at the earliest gestations in this range,” Carlo said.