Dexamethasone and similar drugs have long shown to be effective in saving preterm babies lives in high-income countries, where high-quality newborn care is more accessible.
This is the first time a clinical trial has proven that the drugs are also effective in low-income settings, the study published in the New England Journal of Medicine, reported.
The WHO ACTION-I trial resolves an ongoing controversy about the efficacy of antenatal steroids for improving preterm newborn survival in low-income countries.
Conducted from December 2017-November 2019, the randomised trial recruited 2852 women and their 3,070 babies from 29 secondary and tertiary level hospitals in Bangladesh, India, Kenya, Nigeria, and Pakistan.
Beyond finding a significantly lower risk of neonatal death and stillbirth, the study also found there was no increase in possible maternal bacterial infections when treating pregnant women with dexamethasone in low-resource settings.
"Dexamethasone is now a proven drug to save babies born too soon in low-income settings," said study author Dr Olufemi Oladapo, head of maternal and perinatal health unit at WHO.
"But it is only effective when administered by health-care providers who can make timely and accurate decisions, and provide a minimum package of high-quality care for both pregnant women and their babies," Oladapo added.
The impact is significant: for every 25 pregnant women treated with dexamethasone, one premature baby's life was saved.
When administered to mothers at risk of preterm birth, dexamethasone crosses the placenta and accelerates lung development, making it less likely for preterm babies to have respiratory problems at birth.
The study noted that healthcare providers must have the means to select the women most likely to benefit from the drug and to correctly initiate the treatment at the right time - ideally 48 hours before giving birth to give enough time to complete steroid injections for maximal effect.
Women who are in weeks 26-34 of their pregnancy are most likely to benefit from the steroid, so healthcare providers must also have access to ultrasound to accurately date their pregnancies.
In addition, babies must receive sufficiently good-quality care when they are born, the team said.
"When a minimal package of care for newborn babies is in place in low-income countries, antenatal steroids such as dexamethasone can help to save preterm babies' lives," said study author Dr Rajiv Bahl, head of the newborn health unit at WHO.