Background Hypothalamic-pituitary-adrenal (HPA) axis adaptation is a potential mechanism linking early life exposures with later adverse health. This study tested the hypothesis that preterm birth is associated with adaptation of diurnal cortisol regulation across infancy.
Methods A secondary analysis was conducted of saliva cortisol measured morning, midday and evening, monthly, across infancy, as part of a birth cohort conducted in Linköping, Sweden. Diurnal cortisol regulation of infants born extremely preterm (n=24), very preterm (n=27) and at term (n=130) were compared across infancy through random coefficients regression models.
Results Compared with infants born at term, infants born extremely preterm (−17.2%, 95% CI: −30.7 to −1.2), but not very preterm (1.7%, 95% CI: −14.1 to 20.4), had a flattened diurnal slope across infancy.
Conclusions Extremely preterm birth is associated with a flattened diurnal slope in infancy. This pattern of cortisol regulation could contribute to adverse metabolic and neurodevelopmental phenotypes observed in this population.
- infant development
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RMR and EM are joint senior authors.
Contributors DQS conceptualised and carried out the secondary analysis presented in the manuscript, drafted the manuscript and reviewed and revised the manuscript. JPB, GS, GL, GSB and NZMH contributed to the interpretation of data for the work and revised the article critically for important intellectual content. RMR conceptualised the secondary analysis presented in the manuscript, contributed to the interpretation of data for the work, drafted the manuscript and reviewed and revised the manuscript. NN, ET and EM conceptualised and designed the initial cohort, contributed to the interpretation of data for the work and revised the article critically for important intellectual content.
Funding We are grateful to the families who consented to participate in the cohort. This study was funded by Theirworld (www.theirworld.org) and was undertaken in the MRC Centre for Reproductive Health, which is funded by MRC Centre Grant (MRC G1002033). RMR acknowledges the support of the British Heart Foundation (RE/18/5/34216). EM acknowledge Perth Children’s Hospital Foundation for supporting the professorial position.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.