Birth timing and the mother-infant relationship predict variation in infant behavior and physiology

• Published in: Developmental psychobiology 2013-12, Vol.55 (8), p.829-837
• Main Authors: Vandeleest, Jessica J., Mendoza, Sally P., Capitanio, John P.
• Format: Article
• Language: English
• Subjects: Animals; Behavior, Animal - physiology; birth timing; Cholera Vaccines; coping; cortisol; Female; Hypothalamo-Hypophyseal System - physiology; Hypothalamo-Hypophyseal System - physiopathology; immune system; Macaca mulatta; Male; Maternal Behavior - physiology; Maternal Behavior - psychology; mother-infant relationship; Pituitary-Adrenal System - physiology; Pituitary-Adrenal System - physiopathology; rhesus monkey; Stress, Psychological - physiopathology; Stress, Psychological - psychology; Vaccination
• ISSN: 0012-1630; 1098-2302
• DOI: 10.1002/dev.21074

The current study explored whether birth timing, known to influence the mother–infant relationship, also affected infant physiology up to 9 months later and infant behavior at weaning. Infant blood samples were collected at 5.75 and 8.75 months of age to assess functioning of the hypothalamic–pituitary–adrenal axis as well as the antibody response to a Cholera vaccination. Path analysis indicated infants born late in the birth season had less Relaxed relationships with their mothers. A less‐Relaxed relationship was associated with greater infant Positive Engagement and Distress, which were negatively correlated, suggesting infants may have different strategies of coping with this type of relationship. Low Relaxed scores were also associated with higher infant cortisol concentrations at 5.75 months, which was associated with a reduced immune response to a vaccination 3 months later. Together these results indicate that the influence of birth timing on the mother–infant relationship may have consequences for infant development. © 2012 Wiley Periodicals, Inc. Dev Psychobiol 55: 829–837, 2013.