Infant stress reactivity and prenatal alcohol exposure

Background: Animal studies have shown that prenatal alcohol exposure (PAE) is linked to alterations in the stress response systems. To date, little is known about the impact of PAE on stress systems in human infants. The current study examined PAE effects on the stress response, as evidenced by the activation of the limbic-hypothalamic-pituitary-adrenal (L-HPA) axis and autonomic system and changes in negative affect during a social-emotional challenge in human infants. We also examined whether the effects of PAE on infant responsiveness differed in boys and girls. Methods: Measures of cortisol, heart rate, and negative affect were obtained during a modified version of Tronick's still-face procedure, a standardized developmental paradigm used to study emotion and stress regulation. Our sample included fifty-five 5- to 7-month-old infants whose mothers were enrolled in an alcohol intervention study. Measures of maternal alcohol consumption during pregnancy and after delivery were obtained using Timeline Followback interviewing methods. Relationships between prenatal alcohol consumption and infant outcomes were examined. In addition, mothers were divided into high and low-frequency drinkers, based on the mean percent of prenatal drinking days (PDD) to facilitate between-group comparisons of infant stress measures. Results: Mothers enrolled in our study reported significant reductions in alcohol consumption after learning of their pregnancies. Nevertheless, PDD from conception to pregnancy recognition was related to increases in cortisol reactivity, elevated heart rate, and negative affect in their infants. The effects of PAE on infant responsiveness were significant after controlling for the effects of maternal depression and annual income. In addition, the effects of PAE on cortisol reactivity differed for boys and girls. Conclusions: Greater PAE was related to greater activation of stress response systems. Our findings suggest that PAE affects the development of infant stress systems and that these effects differ in boys and girls. This work supports the possibility that PAE is related to alterations in infant stress systems, which could underlie problems in cognitive and social-emotional functioning that are common among persons exposed prenatally to alcohol.