Vagal tone in infants of depressed mothers

Emotional reactivity and expressivity in infants have been previously correlated with vagal tone. This study investigated vagal tone of 3- and 6-month-old infants of depressed mothers. Vagal tone did not differ for infants of depressed versus nondepressed mothers at 3 months, but lower vagal tone was noted in infants of depressed versus nondepressed mothers at 6 months. The developmental increase in vagal tone that occurred between 3 and 6 months for infants of nondepressed mothers did not occur for infants of depressed mothers. Correlation analyses suggested that higher vagal tone at 6 months was related to more vocalizations and more optimal neurological scores.