The effects of prenatal drug exposure, term status, and caregiving on arousal and arousal modulation in 8-week-old infants.

Prenatal exposure to cocaine, as well as other drugs, has been linked with "dysregulation," usually defined as problems in arousal and/or behavioral regulation. This study was designed to describe the physiological basis of dysregulation as a function of prenatal cocaine/polydrug exposure and term status. Eight-week-old infants were selected because they are just developing the ability to modulate arousal. One hundred-eighteen infants (23 preterm control, 27 preterm drug-exposed, 29 full-term control, and 39 full-term drug-exposed) completed a protocol during which heart rate (HR) and respiratory rate (RR) were measured. Drug group differences were found in baseline, arousal (response to stress), and arousal modulation (recovery from stress). A hierarchical multiple regression analysis was conducted to determine the portion of variance attributable to postnatal caregiving environment, term status, and specific drug exposure. Term status accounted for significant variance in arousal (both RR and HR), and in arousal modulation (only RR). Prenatal exposure to cocaine contributed a significant amount of unique variance in HR arousal whereas tobacco contributed significantly to HR arousal modulation. Prenatal drug exposure and preterm status contributed differently to dysregulation as measured by physiological responses.