London: Steroid injections given to pregnant women before they deliver a premature baby may increase the risk of the child developing behavioural and emotional problems later in life, researchers said on Friday.
Mothers who are expected to give birth prematurely are often given an infusion of glucocorticoids, steroids that mimic the natural hormone cortisol, to try to help the baby's lungs mature more swiftly.
But in a study published in the journal PLOS ONE, scientists found the treatment may also increase the risk of mental health problems including attention deficit hyperactivity disorder (ADHD), a behavioural disorder often diagnosed in children.
"This study suggests there may also be long-term risks for the child's mental health," said Alina Rodriguez, a visiting professor at the School of Public Health at Imperial College London, who led the study.
She added, however, that parents of premature babies should not be unduly concerned because in light of all currently available evidence, the benefits of steroid treatment on the immediate health and survival of a baby are well-established and outweigh any possible risk of long-term behavioural or emotional difficulties.
"Although this is the largest study so far to look at these risks, the number of children in our group who were exposed to glucocorticoids was still relatively small," Rodriguez said. "(So) more studies will be needed to confirm the findings."
Parents concerned their child may be affected should talk to their family doctor for advice, she said.
Cortisol is produced in the fetus in the late stages of pregnancy to help the lungs develop, preparing the baby for life outside the womb.
Lung problems are common in babies born before term and can cause life-threatening breathing difficulties. To reduce the risk of these problems, mothers are given synthetic glucocorticoids, which replicate the effects of natural cortisol, when doctors judge they might have a pre-term birth.
But Rodriguez said concerns have been growing that exposure to high levels of glucocorticoids in the womb might have harmful long-term effects on brain development.
Scientists have previously established a link between stress in pregnancy and symptoms of ADHD in children, and since cortisol is produced as a response to stress, some experts have suggested cortisol may be implicated.
For their study, Rodriguez's team and fellow researchers from Finland's University of Oulu studied 37 children who were exposed to synthetic glucocorticoids before birth and compared them to 185 children who were born at the same gestational age but did not have glucocorticoid treatment.
A large comparison group of 6,079 children, matched for pregnancy and infant characteristics, was also assessed to confirm the findings.
The researchers found the children who had had the steroid treatment had lower scores on general mental health at age eight and 16, and were also more likely to show symptoms of ADHD.
ADHD is one of the most common childhood disorders in the United States, where an average 9 percent of children between the ages of five and 17 are diagnosed with it each year. In Britain experts estimate that between 5 and 10 percent of children and adolescents have ADHD.