Auckland University, April 9, 2017
More New Zealand families could benefit from a life-saving treatment for premature babies as new evidence from a major New Zealand and Australian trial confirms its long-term safety.
The treatment involves injecting pregnant women at risk of giving birth before 35 weeks of pregnancy with corticosteroids (different from muscle-building anabolic steroids). The steroids are synthetic versions of hormones normally released by the mother in late pregnancy.
They flow through the placenta into the baby and speed up the development of her or his lungs, gut, cardiovascular and immune systems, which do not fully mature until after 36 week’.
Every year, around 5000 babies are born prematurely in New Zealand.
Babies whose mothers receive the steroids are less likely to die, less likely to have breathing problems and other serious health problems after birth, and any breathing problems tend to less severe, compared to babies whose mothers do not have the treatment.
A single course of the steroids halves the risk of the most common lung illness in premature babies, called respiratory distress syndrome, from 40 percent to 21 percent in babies born before 32 weeks’.
About twice as many babies will benefit from the treatment when mothers who remain at risk of an early birth receive a repeat dose after seven days.
The problem is, while single courses are routinely given to at-risk women, not all are given repeat doses due to lingering and – it is now clear – misplaced doubts about the long-term safety of this powerful drug.
To check for long-term effects, researchers from Liggins Institute at the University of Auckland, and from the University of Adelaide, have tracked into mid-childhood the health and development of 1000 babies whose mothers either received repeat doses of steroids or a placebo. The trial was called the Australasian Collaborative Trial of Repeat Doses of Corticosteroids (ACTORDS).
The latest study out of the trial, published on April 7, 2017 in top journal Pediatrics, found no difference in the bone health (mass) of children at age six to eight in the treatment and placebo groups.
The main study from the mid-childhood follow-up was published in Pediatrics last October. It showed no adverse effects on brain development and general health.
An earlier study found no adverse effects on cardiovascular and metabolic (gut) health.
As well as showing the immediate benefits of repeat doses to babies, studies from the ACTORDS trial have found no differences in the survival rates, health, development and body size of children whose mothers had received repeat steroids and those who had not received repeat steroids.
Liggins Institute Researcher and Middlemore Hospital Neonatologist Dr Chris McKinlay said that these results should reassure doctors about the short-term benefits and long-term safety of repeat doses, meaning they can use antenatal corticosteroids to their fullest benefit.
“Concerns about the safety of repeat doses partly came from past animal studies that linked repeat doses with later adverse effects on the animal offspring. But ACTORDS is the largest clinical trial of humans in the world to date with school-age follow-up, and it has clearly shown children born to mothers who were given repeat corticosteroids were no more likely to have health or development problems than those born to women who weren’t given repeat doses,” he said.
Professor Caroline Crowther, also from the Liggins Institute, who led the trial, said, “It has been more than 40 years since New Zealand researchers Sir Mont Liggins – the Institute’s namesake – and Ross Howie pioneered the use of corticosteroids.”
“The treatment has saved thousands of lives and dramatically improved the health outlook for many more premature babies around the world – but some families have missed out in the past due to a slow uptake.”
Despite repeated studies confirming the benefits of a single course, it was years before this relatively inexpensive treatment became routine. (Another major Liggins Institute study led by Distinguished Professor Jane Harding, which involved tracking down babies from Liggins’ and Howies’ original trial 30 years later, helped finally turn opinion on the ground).
Last month, Cochrane Collaboration, a global network of scientists that summarises medical evidence for doctors, updated its systematic review of evidence on the treatment, with two Institute experts, Dr Julie Brown and Dr Stuart Dalziel, on the author team.
Dr Chris McKinlay