Monaz: Hello, I'm Monaz Mehta, editor in the Cochrane Editorial and Methods department. One of the earliest Cochrane Reviews studied the effects of steroids for women at risk of a pre-term delivery, and built on an even earlier review. The Cochrane Review has been updated several times and the most recent version was published in December 2020. Two of the authors discuss the latest evidence in this podcast, starting with Emma McGoldrick from the Liverpool Women's NHS Foundation Trust in the UK, who's talking with Fiona Stewart from the Department of Women's and Children's Health at The University of Liverpool.

Emma: Hello Fiona. The issue of whether or not to give antenatal steroid injections to women at risk of preterm birth has been around a long time, and this review of the evidence has its own long history. For people new to the topic, talk us through the background.

Fiona: Hello Emma. The use of antenatal steroids for women at risk of preterm birth was actually the subject of one of the very first systematic reviews and meta-analyses, back in the 1980s. In fact, the Cochrane logo comes from this review and shows what the forest plot analysis would have looked like if the evidence had been analysed together in 1982. When the first full systemic review and meta-analysis was actually published, in 1989, the conclusion was that steroids reduced the risk of death and serious illness in babies, but there were still many uncertainties and in the thirty years since then, more studies have been done and the review has been regularly updated.

Emma: Looking to the most recent update, what does it tell us?

Fiona: The review now has 27 trials, with a total of more than 11,000 pregnant women and their babies. It provides high-certainty evidence that antenatal steroids reduce the risk that the baby will die immediately before birth or in their first month. There's also high-certainty evidence that antenatal steroids reduce the risk of the baby developing serious respiratory difficulties and that there is little to no effect on birthweight.

Emma: That's certainly good news for babies and their mothers. Is there any information about the effects on pregnant women?

Fiona: We looked at the risk of maternal death and infection and found there is probably little to no difference between women who receive steroids and those who don't. I say 'probably' little to no difference because the certainty of this evidence is moderate, in contrast to the high certainty evidence we found for the main outcomes for the babies.

Emma: Are there any other important new findings from this update of the review?

Fiona: Something that was missing in the earlier versions was evidence on what happens in low- and middle-income countries. Until recently, the available evidence was generally only from high-income countries but we've now been able to add a substantial amount of data from trials in lower resource settings. This shows that the results are broadly similar to the trials in higher-income countries, so we can be more certain about our conclusions and more confident that the findings are applicable to a broad range of settings.

Emma: It's clear that the review is continuing to provide important new information, but are there any remaining uncertainties about the effects of antenatal steroids?

Fiona: Yes, even though lots of progress has been made there are still some things we don't know. For example, the evidence isn't completely clear about the effects in specific high-risk groups, such as women with diabetes, high blood pressure or multiple pregnancies. It's also important to keep following up the infants in the trials that have been done, so that we can find out more about the long-term effects and find out what happens to these babies as they become children and adults.

Emma: Thanks Fiona. It sounds as though there's still work to do and more updates to come. If people want to read the current version and watch out for those future updates, where can they find it?

Fiona: The review is available online. Just go to cochrane library dot com. Type 'antenatal steroids and preterm birth' into the search box the review will appear at the top of the list.