Development of salivary cortisol circadian rhythm in preterm infants

Katrin Ivars; Nina Nelson; Annette Theodorsson; Elvar Theodorsson; Jakob O Ström; Evalotte Mörelius

doi:10.1371/journal.pone.0182685

Development of salivary cortisol circadian rhythm in preterm infants

PLoS One. 2017 Aug 10;12(8):e0182685. doi: 10.1371/journal.pone.0182685. eCollection 2017.

Authors

Katrin Ivars¹, Nina Nelson^{1

2}, Annette Theodorsson³, Elvar Theodorsson⁴, Jakob O Ström^{4

5}, Evalotte Mörelius⁶

Affiliations

¹ Department of Pediatrics and Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden.
² Department of Quality and Patient Safety, Karolinska University Hospital, Stockholm, Sweden.
³ Department of Neurosurgery and Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden.
⁴ Department of Clinical Chemistry and Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden.
⁵ Department of Neurology, Faculty of Medicine and Health, University of Örebro, Örebro, Sweden.
⁶ Division of Nursing Science, Department of Social and Welfare Studies, Linköping University, Norrköping, Sweden.

Abstract

Objectives: To investigate at what age preterm infants develop a salivary cortisol circadian rhythm and identify whether it is dependent on gestational age and/or postnatal age. To evaluate whether salivary cortisol circadian rhythm development is related to behavioral regularity. To elucidate salivary cortisol levels in preterm infants during the first year of life.

Methods: This prospective, longitudinal study included 51 preterm infants. 130 healthy full-term infants served as controls. Monthly salivary cortisol levels were obtained in the morning (07:30-09:30), at noon (10:00-12:00), and in the evening (19:30-21:30), beginning at gestational age week 28-32 and continuing until twelve months corrected age. Behavioral regularity was studied using the Baby Behavior Questionnaire.

Results: A salivary cortisol circadian rhythm was established by one month corrected age and persisted throughout the first year. The preterm infants showed a cortisol pattern increasingly more alike the full-term infants as the first year progressed. The preterm infants increase in behavioral regularity with age but no correlation was found between the development of salivary cortisol circadian rhythm and the development of behavior regularity. The time to establish salivary cortisol circadian rhythm differed between preterm and full-term infants according to postnatal age (p = 0.001) and was dependent on gestational age. Monthly salivary cortisol levels for preterm infants from birth until twelve months are presented. Additional findings were that topical corticosteroid medication was associated with higher concentrations of salivary cortisol (p = 0.02) and establishment of salivary cortisol circadian rhythm occurred later in infants treated with topical corticosteroid medication (p = 0.02).

Conclusions: Salivary cortisol circadian rhythm is established by one month corrected age in preterm infants. Establishment of salivary cortisol circadian rhythm is related to gestational age rather than to postnatal age. Salivary cortisol circadian rhythm development is not related to behavioral regularity.

MeSH terms

Adult
Case-Control Studies
Child Development
Circadian Rhythm*
Female
Gestational Age
Humans
Hydrocortisone / metabolism*
Infant
Infant, Newborn
Infant, Premature / growth & development
Infant, Premature / metabolism*
Longitudinal Studies
Male
Prospective Studies
Saliva / metabolism*

Substances

Hydrocortisone

Grants and funding

This study was supported by the County Council of Östergötland, Sweden and Medical Research Council of Southeast Sweden, FORSS (FORSS-8396, FORSS-12268, FORSS-37391, FORSS-78011). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.