Drugs given to expectant mothers that can save the life of very preterm babies are harmful to infants who manage to stay in the womb full-term, a new study has found.
The researchers caution that obstetricians must be more selective in predicting whether a baby is likely to be born early, in which case they would prescribe steroids.
"Preterm birth is very challenging to predict. We need better prediction models to avoid over-exposure to interventions like steroids as there may be a potential risk," said study leader Sarah McDonald of McMaster University in Hamilton, Ontario, Canada in a statement.
If a baby is at risk of being born too early - before 34 weeks of pregnancy - giving the mother steroids before the birth helps the lungs to develop more quickly, reducing the risk of serious complications or death.
When researchers analyzed data from previously published studies involving a total of 1.6 million infants born since 2000, they found about 2% had been exposed to steroids in the womb - but roughly 40% of the babies whose mothers received corticosteroids were actually born at term.
The full-term infants exposed to steroids in the womb had an increased risk of health issues, including neonatal intensive care unit admission, respiratory and growth issues, and adverse neurodevelopmental outcomes, the researchers reported on Wednesday in The BMJ.
A separate study published in the same issue of the journal found that babies exposed in the womb to one course of corticosteroids were significantly more likely to have an increased risk of serious infection during the first 12 months of life.
"Antenatal steroids are a double-edged sword: very beneficial for babies born very early, and potentially harmful for babies born at term," McDonald said.
