Effects of Antenatal Corticosteroids on Cortisol and Heart Rate Reactivity of Preterm Infants

Administration of glucocorticoids (GCs) during pregnancy is an established practice for reducing morbidity and mortality of fetuses at risk of preterm delivery. However, preliminary research indicates that exposure to exogenous GCs in utero may be associated with suppressed hypothalamic-pituitary-adrenal axis activity. The aim of this study was to determine whether preterm neonates who are exposed to antenatal corticosteroids show evidence of a suppressed stress-response system during their first few weeks of life, in contrast to infants who are not exposed. The sample (51% female) included 57 neonates, with 74% exposed to steroids. Mean gestational ages (GAs) were 32.6 weeks for exposed and 34.7 weeks for nonexposed infants. Although neonates in the two groups differed in gender, birth weight, and morbidity, these factors were controlled for in data analyses. Infants' salivary cortisol and heart rate (HR) were measured before and after they received a standardized caregiving stressor while in the newborn intensive care unit. Infants exposed to GCs in utero had lower basal cortisol levels and higher HRs than their nonexposed peers. In contrast to infants who received no GCs, they also exhibited minimal HR or cortisol reactivity to the stressor. Findings suggest that preterm infants who were exposed to antenatal corticosteroids experience a suppressed response to stress. As preterm children develop, this dysregulation has numerous implications for later development of stress-related cardiovascular and mental health problems. Further research is needed to determine whether these postnatal effects of antenatal corticosteroids persist over time.