Prenatal origins of temperamental reactivity in early infancy

Background: Temperament theory has long considered individual differences in reactivity and regulation to be present at birth. Recent evidence suggests that such differences may be present prenatally and moderated by maternal emotionality. Aims: To determine whether induced maternal emotional activation generates a fetal response and whether observed fetal responsivity is associated with early infant temperament. Study design: Women viewed an emotionally evocative labor and delivery documentary at 32 weeks gestation while physiological indices were evaluated and their infant's temperament was assessed at 6 weeks postnatal age. Subjects: Participants were 137 pregnant women and their infants. Outcome measures: Maternal physiological (heart rate and skin conductance) and fetal neurobehavioral (heart rate and motor activity) data were collected during gestation in response to the stimulus. Infant temperament (irritability and consolability) data were based on observational methods after birth. Results: Fetuses reacted to maternal viewing of the video with decreased heart rate variability, fewer motor bouts, and decreased motor activity. There was correspondence between the nature of individual maternal physiological responses to the full video, as well as phasic responses to a graphic birth scene, and fetal responsivity. Fetuses that reacted more intensively to maternal stimulation were significantly more likely to become infants that demonstrated greater irritability during a developmental examination at 6 weeks of age. Discussion: These results support the presumption that early postnatal temperamental characteristics emerge during the prenatal period.