Studies have confirmed the long term safety of a life-saving treatment for premature babies.
Caroline Crowther, from the Liggins Institute, has led a 10-year trial for repeat doses of corticosteroids for pregnant mothers in danger of having a premature birth.
She said the drug sped up the development of the baby's lungs, gut and immune systems, which normally did not fully mature until after 36 weeks.
Professor Crowther said more than 1000 women across Australia and New Zealand were given the steroids, and researchers followed up with their children when they were six to eight years old.
She said none of the children had had harmful side effects.
"The short term benefits are really very dramatic, we've got a halving of the problems that those tiny babies have, particularly the breathing problems, and in terms of their follow-up later on we're not seeing any harmful effects at all."
One mother who trialled repeat doses of corticosteroids during pregnancy due to the danger of a premature birth has recommended women take the drug.
Hilary Jenkins said her son, Connor, was born about 10 weeks premature but the corticosteroids helped him to develop normally.
"We really do think that the ability to have the extra help through the extra steroids has really helped him compared to children that don't have it.
"We've got another child who was prem as well, he didn't have any steroids at all, and he struggled quite a lot."
Ms Jenkins said her son was now a healthy and happy 13-year-old boy who no one would guess was born prematurely.