Maternal endocrine activation during pregnancy alters neurobehavioral state in primate infants

The purpose of this study was to investigate whether maternal endocrine activation during pregnancy would affect the neurobehavioral state of primate offspring in a manner similar to that observed in human infants from pregnancies involving maternal substance abuse or maternal stress.

Twenty-two rhesus monkey (Macaca mulatta) infants were derived from females administered either adrenocorticotrophic hormone (ACTH), which increased the mother's endocrine activity, or saline solutions for 14 consecutive days during mid-pregnancy. On days 15 and 30 postpartum, infants underwent brief separations from their mothers and were videotaped for later evaluation of neurobehavioral state.

Infants from mothers administered ACTH spent significantly more time in a drowsy state than did controls (p < .04), and the increased drowsiness tended to be most pronounced during the postseparation period, when acute stress was highest. In contrast, controls remained in a more active alert state (p < .03), presumably searching for their mother, a species-typical adaptive response to maternal separation. Female infants spent more time in distressed state than did males on day 15, and the proportion of time in distressed state decreased in all infants after administration of .2 ml of 24% sucrose solution.

The results demonstrate that neurobehavioral state alterations are found in infants from mothers with increased endocrine activity during pregnancy. Neurobehavioral state disorganization can have an adverse impact on the human infant's concurrent and subsequent occupational performance. These findings establish the usefulness of the nonhuman primate model for advancing knowledge on early contributions to the development of human infant occupational behavior.