Chorioamnionitis, cortisol, and acute lung disease in very low birth weight infants

To explore the relationship between chorioamnionitis, postnatal cortisol concentrations, and acute respiratory distress in very low birth weight infants.

Appropriate for gestational age infants weighing between 501 to 1500 g at birth were enrolled into this prospective, observational study, and data regarding respiratory distress on the first day of life were recorded. Serum cortisol concentrations were measured on (a) day 2, (b) day 3 or 4, and (c) day 5, 6, or 7 of life. On day (b) or (c), 3.5 microg/kg of cosyntropin (an adrenocorticotrophic hormone analog) was given, and a repeat specimen was drawn 30 minutes later. Chorioamnionitis was diagnosed by placental examination by one author (R.L.N.).

Forty-two infants exposed to chorioamnionitis and 37 infants not exposed were enrolled. Chorioamnionitis correlated inversely with gestational age, and was associated with decreased measures of acute respiratory support (exogenous surfactant, fraction of inspired oxygen, and ventilator support at 12 and 24 hours). Infants with chorioamnionitis had higher cortisol concentrations, both basal and stimulated. Gestational age was not significantly related to basal cortisol, but did correlate positively with stimulated values. Cortisol values from the 16 infants exposed to prenatal glucocorticoid therapy were excluded from these analyses.

These results provide evidence that prenatal inflammation leads to adrenal stimulation, resulting in increased cortisol secretion and accelerated lung maturation. The enhanced response to cosyntropin stimulation seen in these infants may reflect an increased adrenal capacity to respond to postnatal stressors. Because of the apparent magnitude of the effect of chorioamnionitis on cortisol measures, this factor should be included in future investigations of adrenal function in very low birth weight newborns.