Effects of prenatal betamethasone exposure on regulation of stress physiology in healthy premature infants

Antenatal betamethasone treatment has a persisting influence on infant HPA axis regulation

“…¼ 0.5) weeks of gestation without AB treatment who were not ill in the postnatal period. This group's neonatal data have been previously reported 5 and are used here to provide a postconceptional age-matched comparison group for the follow-up assessment of the experimental group.…”

“…4 Both full-term and preterm newborns, without GC treatment, respond to painful stressors with an increase in cortisol production, as indicated by salivary or serum concentrations. 5,6 This is thought to be an appropriate response given the role that cortisol plays in mobilizing resources to manage physiologic challenges.…”

“…[7][8][9] However, those studies did not assess the responsiveness of the system to a physiologic challenge and thus did not evaluate the axis' ability to react in its normal biological role. Other studies suggest that prenatal GC treatment suppresses the ability to increase cortisol production in response to a physiologic challenge or CRH stimulation, but these studies only assessed the infants during the first postnatal week 5,10 and did not assess how long this suppression persists. Thus, the longer-term consequences of prenatal GC treatment for regulation of the HPA axis in response to commonly encountered physiologic challenges have yet to be examined in the human infant.…”

“…This stressor was selected because it reliably elicits a significant increase in cortisol production, as compared to baseline levels, in both fullterm and preterm infants without prenatal GC treatment. 5,6 We hypothesized that (1) infants in the AB group would fail to increase cortisol in response to the heelstick during the first postnatal week, (2) the cortisol response would remain suppressed 4-6 weeks later and (3) the effects of AB would prove to be specific to the HPA axis and thus, that both groups would show similar increases in heart rate (HR) and behavioral state in response to these events.…”

The challenge of defining relative adrenal insufficiency

“…A concern has previously been raised for attempting to base a definition of relative adrenal insufficiency on cortisol values obtained shortly after birth owing to the potential for suppression of the hypothalamic-pituitary-adrenal axis from maternal steroid administration. 8,9 The population presented in this study has predominantly been exposed to prenatal steroids (over 90% in both groups), allowing for a realistic evaluation comparable to the dilemma confronted by clinicians. Clearly, there is an advantage to an early diagnosis of relative adrenal insufficiency to allow appropriate clinical decision making, as shown in this study by approximately one third of the infants receiving inotropes in the first 24 h of life.…”