Steroid treatment for prematurity put to the test

Babies whose mothers received steroid injections before giving birth have no higher risk of heart disease at age 30 than those whose mothers received a placebo treatment.

This result comes from a University of Auckland study, published in The Lancet on 28 May, of 30-year-olds whose mothers received either steroid or placebo injections when they went into premature labour.

The Lancet study did, however, discover indicators of possible mild insulin resistance in people whose mothers received the steroid.

Steroid treatment of women in premature labour is standard international practice, and speeds up the maturation of the babies’ lungs. Until now there has been almost no information about how these babies do as adults.

The treatment’s effectiveness was first demonstrated at Auckland’s National Women’s Hospital by Professors Sir Graham Liggins and Ross Howie in a clinical trial published in 1972, a time when most very premature babies died of respiratory distress. This simple treatment halved the babies’ death rate. It has subsequently saved hundreds of thousands of lives worldwide.

Researchers from the Clinical Trials Research Unit and the Liggins Institute, of The University of Auckland’s Faculty of Medical and Health Sciences, launched the Lancet study due to concern that fetuses exposed to steroids may grow up with an increased risk of disease.

For the Lancet study, 534 of the babies who were born while their mothers took part in the original Liggins and Howie trial were tracked down and tested in 2002 and 2003, at age 30. This was a remarkable feat because all that was known about them to start with was their date of birth, sex, and mother’s surname at the time they were born.

It is one of the longest follow-up periods ever undertaken following a trial conducted in pregnancy.

Author Professor Jane Harding, a neonatologist and Liggins Institute Deputy Director, says that the advantages of the treatment vastly outweigh any possible disadvantages. “This is a treatment that dramatically reduces the chances that a premature baby will have lung disease, bleed into its brain, or even die. We can now be confident that this treatment is also very safe, resulting in no increased health risk up to 30 years of age.”

“The finding of insulin resistance provides the first proof in humans that exposure to steroids before birth might permanently alter metabolism,” says lead author Dr Stuart Dalziel, a Research Fellow at the Clinical Trials Research Unit.

The other authors are Natalie Walker, Varsha Parag, Colin Mantell, Harold Rea and Anthony Rodgers. The study was supported by the Health Research Council of New Zealand, the Auckland Medical Research Foundation and the New Zealand Lottery Grants Board.

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