Abstract
ObjectivesTo 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.MethodsThis 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.ResultsA 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).ConclusionsSalivary 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.
Highlights
Cortisol is considered a major biomarker of stress among children and adults [1, 2]
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
Summary
Cortisol is considered a major biomarker of stress among children and adults [1, 2]. The fetal hypothalamic-pituitary-adrenal (HPA) system responsible for cortisol release is functional by the beginning of the second trimester [3]. Cortisol is secreted in a pulsatile fashion in a circadian rhythm, peaking in the morning and displaying a nadir in the evening [4], from age one month in healthy full-term infants [5]. To further understand the development of cortisol expression in infants born preterm it is important to investigate when cortisol circadian rhythm (CCR) is established. Antonini et al included infants (n = 9) born between 31 and 34 weeks GA and followed them longitudinal from two to 24 weeks of postnatal age. They found that salivary CCR emerged between eight and 12 postnatal weeks [8]. The remaining four studies did not confirm CCR during the study periods, which varied between one and four postnatal weeks [6, 9,10,11]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
