Comparisons were made of differences in the hormonal sensitivity of preterm versus full-term infants to maternal depression, as reflected in children's cortisol levels. In Study 1 (N = 25), a comparison was made between preterm versus healthy full-term children. In Study 2 (N = 80), a comparison was made between preterm infants and full-term infants with mild or moderate medical problems. Preterm infants were found be highly reactive to maternal depression (as measured by the Beck Depression Inventory). That is, they demonstrated higher cortisol levels when paired with depressed mothers and lower cortisol levels when paired with non-depressed mothers. No equivalent effects were found for children who were full-term, even when they had experienced other medical problems at birth. It was concluded that premature infants are exceptionally sensitive to the "emotional climate" in their home environment. As a result, they may manifest very different hormonal outcomes --with implications for their later development.Considerable attention has been given historically to the fact that high levels of stress early in life predict later problems. More recently, such effects have been interpreted in terms of biological changes as mediators of this process. Researchers concerned with developmental psychopathology have given increasing attention to the neurohormonal responses of very young children to early trauma or stress (e.g., Bremner & Narayan, 1998;Gunnar, 2000; Nelson, 2000). However, interests have expanded beyond concern with trauma to a broader consideration of early experiences that predict children's later outcomes. It has also extended to consider possible variations in child vulnerability. Repetti, Taylor and Seeman (2000), in a review of literature concerning the biological outcomes of children in "risky" families (e.g., those characterized by aggression/conflict or coldness/neglect), concluded that child vulnerability and family risk combine to predict dysregulation of the child's stress response system --a consequence that ultimately has negative implications for their later health and well-being. In this study, we focused attention on maternal depression as a potential source of early stress for infants. Our specific concern here was on the differential vulnerability of preterm versus full-term infants to maternal depression -in terms of their stress-relevant hormonal responses.Maternal Depression-Maternal depression has repeatedly been found to have negative implications for maternal responsiveness and sensitivity to infants -which in turn has Corresponding author: Daphne Bugental, Department of Psychology, University of California, Santa Barbara, CA 93106, Email: bugental@psych.ucsb.edu, David A. Beaulieu, Department of Psychology, University of California, Santa Barbara, CA 93106, Email: beaulieu@psych.ucsb.edu, Alex F. Schwartz, Department of Psychology, University of California, Santa Barbara, CA 93106, Email: schwartz@psych.ucsb.edu. Publisher's Disclaimer: This is a PDF file of an unedited ma...