THURSDAY, SEPTEMBER 12, 2019
Two common forms of a life-saving steroid treatment for preterm babies have been shown to be equally effective and safe
in a large New Zealand-Australian clinical trial – though the cheaper one may have a slight advantage.
The treatment, discovered by New Zealand scientists Sir Mont Liggins and Ross Howie in 1972 and now internationally
recommended practice, involves injecting pregnant women at risk of giving birth before 35 weeks’ gestation with
corticosteroids (different from muscle-building anabolic steroids). The steroids - synthetic versions of hormones
normally released by the mother in late pregnancy - speed up the development of the baby’s lungs, gut, cardiovascular
and immune systems, which do not fully mature until after 36 weeks.
Worldwide, just under 10 percent of babies are born preterm every year. In Aotearoa New Zealand 7.5 percent of all
births, or 4,500 babies, are born prematurely each year, with about half of these born very early at less than 34 weeks.
Babies born early often have breathing problems and require neonatal intensive care. Not all babies born early survive
and those that do are at increased risk of later developmental problems.
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 be less severe, compared with babies whose
mothers do not have the treatment.
But, controversy remains about which of the two types of corticosteroids commonly used in this treatment – dexamethasone
and betamethasone – to use, and how best to use them. There’s also a big price difference: a full course of
dexamethasone costs about US$1 (NZ$1.50) versus US$35 (NZ$54) for betamethasone.
“Worldwide, hundreds of thousands of mothers are at risk of preterm birth, so it’s really important that we know the
best drug to use for both mothers and babies’ health,” says Liggins Institute Professor Caroline Crowther, a world
expert in this field.
Professor Crowther and her collaborators set up an Australian-New Zealand clinical trial, the largest of its kind to
date, to find out which drug provides the best chance of the baby surviving and being healthy in early childhood. The
double-blind, randomised trial, dubbed the ‘Asteroid Trial’, involved 1346 mothers and their 1509 babies at 14 hospitals
in the two countries, including Auckland City Hospital. Half the mothers received one drug, half the other. Researchers
assessed the mother’s health, and the babies’ health following birth and at age two.
The results, published in prestigious medical journal The Lancet Child and Adolescent Health
, showed that overall, antenatal dexamethasone and betamethasone were similar at improving the chances of babies
surviving and being free of disability in early childhood. Health for the babies after birth and up to two years was
Dexamethasone showed a few advantages: children exposed to this drug were less likely to have high blood pressure (32
percent versus 41 percent), and fewer women who received it had a caesarean birth (43 percent versus 52 percent) and
experienced pain at injection (1 percent versus 3 percent).
“Our findings give welcome reassurance that the two drugs have similar beneficial effects on newborns’ health and
development in early childhood,” says Professor Crowther. “Further research is needed to understand the observed
differences in childhood hypertension and caesarean birth rates and to assess any possible later effects. In the
meantime, perhaps cost and local availability should be the deciding factor between the two drugs.”
The research was funded Australia’s National Health and Medical Research Council.