Early hydrocortisone treatment of extremely premature babies increases their chances of survival without lung disease, according to a study led by Linköping University. The study also shows that the treatment is safe to give. The results are published in JAMA Network Open.
More than half of babies born extremely prematurely – before 28 weeks of pregnancy – get a lung disease called bronchopulmonary dysplasia, BPD, which often affects them for the rest of their lives. The disease occurs because very premature babies' lungs are not fully developed. Several factors can make the lungs brittle and impair lung tissue development.
A key factor in BPD is inflammation, which damages the lung tissue. The hormone cortisone suppresses inflammation, but babies born extremely prematurely cannot produce enough cortisone. Previous studies investigating preventive hydrocortisone treatment have indicated positive effects, but have also raised concerns of severe side effects. The treatment is being used in several countries. In Sweden, some regions have in recent years introduced guidelines on hydrocortisone treatment from the first day after birth, while other regions have chosen to abstain.
"This has led to a kind of natural experiment in Sweden, where some extremely premature babies have been treated and others not. We took advantage of this in our study, where we looked at how this treatment works in real healthcare situations in Sweden. There are almost no such studies in the world today," says Ulrika Ådén, professor of paediatric medicine at Linköping University and Karolinska Institutet, and chief physician in neonatology, who led the study published in JAMA Network Open.
The researchers analysed data from the national neonatal registry. A total of 474 children who had received hydrocortisone treatment were compared with 632 children born in the same region before the introduction of this treatment. They also compared with regions not providing hydrocortisone treatment. All babies were born in weeks 22 to 27 of pregnancy, between 2018 and 2023.
"Our study shows that providing this treatment to extremely premature babies early in life increases their chance of surviving without lung disease. Hydrocortisone treatment is safe to administer and does not increase the risk of serious side effects during the newborn period, says Veronica Smedbäck, PhD student at Linköping University and physician.
Many children who get bronchopulmonary dysplasia are at increased risk of getting infections and being hospitalised during school age. This lung disease is also linked with children not gaining weight as expected and with negative effects on brain development. The researchers believe that preventive treatment can be important for children and their families, and for society at large, as it could reduce these children's need for care.
"Given that more than half of all extremely premature babies are affected by this lung disease, this treatment may be valuable, as it increases the chance of survival without the disease. Many countries today save extremely premature children, so this could potentially affect a very large number of children," says Veronica Smedbäck.
The study looks at short-term safety aspects of the treatment. The researchers will now investigate possible longer-term effects of the treatment, where one important aspect is brain development. Other studies have indicated that the treatment has a positive effect on brain development, but more research is needed on its long-term effects.
The study was supported by the Joanna Cocozza Foundation for Child Medical Research and an ALF research grant through Region Östergötland.
Article: Early prophylactic hydrocortisone, broncopulmonary dysplasia, and survival in extremely preterm infants , Veronica Smedbäck, Lars Björklund, Anders Flisberg, Jolanta Wróblewska, Olivier Baud, Erik Wejryd and Ulrika Ådén, (2026), JAMA Network Open, published online 19 February 2026, doi: 10.1001/jamanetworkopen.2025.60146
