Maternal variables associated with physiologic stress and perinatal complications in preterm infants.

OBJECTIVE: Complications of prematurity may be related to dysregulation of the hypothalamic-pituitary-adrenal axis in preterm infants. Increased intrauterine exposure to cortisol may be responsible for adverse prenatal programming and subsequent dysfunction of the infant's hypothalamic-pituitary-adrenal axis. The aim of the study was to describe maternal social variables and their association with infant cortisol levels and complications of prematurity. METHODS: Preterm infants <32 weeks' gestation were recruited. Primary outcomes were development of complications of prematurity and physiologic stress response, represented by cord blood and salivary cortisol levels on first day of life. Descriptive statistics and comparative analyses were performed. RESULTS: Fifteen of 31 infants enrolled developed a complication of prematurity. Infants of greater gestational age when prenatal care was established had lower cord blood cortisol (p = 0.009) and trended a higher risk of necrotizing enterocolitis (p = 0.069). Infants whose mothers smoked more showed significantly different salivary cortisol distributions on day 1 (p = 0.037), and were at greater risk for intraventricular hemorrhage (p = 0.018). CONCLUSIONS: The association between maternal social variables, hypothalamic-pituitary-adrenal axis dysregulation, and complications of prematurity supports the research model of physiologic dysregulation/allostatic load as a mechanism for complications in preterm infants. More research is warranted to investigate associations between maternal social variables, maternal stress levels, and adverse prenatal programming of the infant hypothalamic-pituitary-adrenal axis.