Preterm birth, where a baby is born before 37 weeks, is one of the major reasons babies die today.
One in 10 babies is born preterm in high-income countries, and that rises to four in 10 in low and middle-income countries.
These babies are extremely vulnerable because they miss out on a crucial final development stage in which the hormone cortisol is released exponentially into the unborn baby’s blood.
Cortisol is vital for the maturing of organs and systems needed to keep the baby alive once born.
For example, in the lungs, cortisol ensures they become more elastic. This allows the lungs to expand so the baby can take its first breath.
Without cortisol, the newborn lungs would be too stiff, which leads to respiratory distress syndrome and could be fatal.
The established treatment for any pregnancy threatened with preterm birth is steroids, given via the mother before the baby is born and/or directly to the baby after birth.
These steroids speed up the development of organs – including the lungs – which means the preterm baby is much more likely to survive.
However, according to lead author Professor Dino Giussani of Cambridge University, this cortisol can be damaging to the heart: “It resembles accelerated ageing,” he says.
Potentially life-saving steroids, commonly given to preterm babies, also increase the risk of long-term heart problems, but a study in rodents has found if they’re given alongside statins, their positive effects remain while the potential negative side effects are “weeded out”.
A previous clinical study by Professor Paul Leeson’s laboratory at Oxford University, found that people who had been exposed to glucocorticoid (steroid) therapy as unborn babies, via their mothers, had hearts 10 years older than normal.
Cambridge researcher Dr Andrew Kane believes this is due to a reduction in nitric oxide. This is beneficial to the cardiovascular system as it increases blood flow and is anti-inflammatory.
To test if a lack of nitric oxide could be the origin of the cardiovascular side effects of steroids, researchers combined the steroid treatment with statins, which are widely used to lower cholesterol and are known to increase nitric oxide.
“Our discovery suggests that combined glucocorticoid (steroid) and statin therapy may be safer than glucocorticoids alone for the treatment of preterm babies,” said Prof Giussani.
Combining steroids with statins, he adds, “gives us the best of both worlds – we can maintain the benefits of steroids on the developing lungs, but ‘weed out’ their adverse side effects on the developing heart and circulation, thereby making therapy much safer for the treatment of preterm birth.”