News Release

Infants exposed to corticosteroids in utero are smaller at birth, study finds

Peer-Reviewed Publication


Infants exposed to antenatal corticosteroid therapy (ACT) to accelerate lung maturation have a clinically significant reduction in birth size, according to a new of study of 278,508 births published this week in PLOS Medicine by Alina Rodriguez of the University of Lincoln and Imperial College London, UK, and colleagues.

Guidelines currently recommend one dose, repeated over 24 hours, of ACT to accelerate lung maturation in cases of threatened preterm birth. However, many exposed infants end up born at term and are therefore exposed unnecessarily to any potential harms of ACT. In the new study, researchers studied all live-born singleton births in Finland from 2006 through 2010. De-identified data were available on ACT exposure, birth weight, birth length, head circumference, Apgar scores, and medical care of infants.

4,887 women (1.75%) were treated with ACT and, of those exposed, more than 44% (2173) of infants were born at term. Adjusted analyses showed significant differences in birth weight between exposed and unexposed infants, with an apparent reduction in birth weight of 61.54 grams for very preterm babies exposed to ACT (±SE 28.62, P<.03), 222.78 grams for preterm babies (±SE 19.64, P<.001), 159.25 grams for near term babies (±SE 19.14, P<.001), and 91.62 grams for term babies (±SE 11.86, P<.03). Associations were also seen for birth length and head circumference. There were no significant differences in Apgar scores, but ACT-exposed infants generally required greater medical care during the first seven days of life and beyond.

"These findings provide strong evidence indicating that ACT is associated with reduced fetal growth in humans and provide an agenda for further studies," the authors say. "Early care decisions need to identify high-risk patients and weigh benefits of ACT against potential harm of unnecessary exposure."


Research Article


Funding for this research was provided by Swedish Research Council for Health, Working Life, and Welfare (FAS 20111483; and VINNOVA Sweden's Innovation Agency (200801003;, both to AR; Academy of Finland EGEA project (285547; and EU H2020 LifeCycle Action (grant agreement 733206) to MRJ; and EU H2020 DynaHEALTH action (grant agreement 633595; to MRJ (PI) and AR (collaborator). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing Interests:

The authors have declared that no competing interests exist. YW and AAK conducted this work while at Imperial College London and subsequently moved to Novartis Pharma AG, Basel, Switzerland, and Apple Tree Pediatrics, Karachi, Pakistan, respectively. Neither Novartis nor Apple Tree Pediatrics was involved in this research or has a financial stake in this work.


Rodriguez A, Wang Y, Ali Khan A, Cartwright R, Gissler M, Järvelin M-R (2019) Antenatal corticosteroid therapy (ACT) and size at birth: A population-based analysis using the Finnish Medical Birth Register. PLoS Med 16(2): e1002746.

Author Affiliations:

Department of Epidemiology and Biostatistics, Imperial College London, London, United Kingdom

School of Psychology, University of Lincoln, Lincoln, United Kingdom

Department of Obstetrics and Gynaecology, Oxford University Hospitals NHS Trust, Oxford, United Kingdom

Information Services Department, THL National Institute for Health and Welfare, Helsinki, Finland

Department of Neurobiology, Care Sciences and Society, Division of Family Medicine, Karolinska Institute, Stockholm, Sweden

Unit of Primary Health Care, Oulu University Hospital, Oulu, Finland

Biocenter Oulu, University of Oulu, Oulu, Finland

Center for Life Course Health Research, Faculty of Medicine, University of Oulu, Oulu, Finland

Department of Life Sciences, College of Health and Life Sciences, Brunel University London, London, United Kingdom

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