While it is fairly obvious that postpartum depression can hinder a mother’s ability to take care of her newborn, a new study looks at how the disorder can affect infant development.

Israeli researchers studied three infant outcomes — social engagement, fear regulation, and physiological stress reactivity — in a group of 100 mother-infant pairs at nine months postpartum. These three infant outcomes are considered foundations of social-emotional growth and are associated with the infant’s ability to manage physiological stress and regulate negative emotions.

The researchers found that the babies of depressed mothers scored the poorest on all outcome measures after 9 months. The infants showed the lowest levels of social engagement during interactions with their mothers, were unable to self-regulate during situations that introduced novelty, fussed and cried more often, and their physiological stress response showed both higher baseline levels and a more pronounced stress reactivity.

The researchers collected a large community cohort of 971 mothers who reported symptoms of depression and anxiety at 2 days postpartum and again at 6 months. Of these, a cohort of 100 mothers and infants were observed at 9 months and included three groups: Mothers who were depressed across the first nine months and were diagnosed as suffering a Major Depression Disorder at 9 months, mothers who reported high levels of anxiety across the first 9 months and were diagnosed with an Anxiety Disorder at 9 months, and control mothers who reported low anxiety and depressive symptoms across the first 9 months after childbirth.

To remove the influence of other known risk factors such as teenage pregnancy or premature birth, which could independently contribute to maternal depression, the researchers only recruited women who were in stable relationships, were physically healthy, educated, and those who delivered a healthy full-term infant.

Children of anxious mothers showed lower social engagement than children of control mothers but higher than children of depressed mothers. However, their physiological stress response was similar to children of depressed mothers.

The mother’s sensitive behavior played an important role in shaping infant outcomes. Sensitive mothering was related to the infant’s social engagement and protected against the effects of maternal depression on the development of the child’s social skills.

Maternal sensitivity also had a positive impact on the infant’s physiological stress response and reduced the degree of physiological reactivity as measured by cortisol reactivity to stress.

Sensitive mothering is important in an infant’s ability to develop social competence and further study of the effects of maternal depression on child development within the first year of life is warranted.

Feldman and colleagues stated, “By recruiting a large community sample, separating maternal depression from typically-occurring conditions, comparing cases of major depressive disorder to those of postpartum anxiety disorders, and assessing the chronicity of the mother’s mood from birth, the findings may illuminate specific pathways leading from maternal depression to child outcomes across the first year of life.

“Furthermore, the unique associations found between maternal depression and each outcome underscore the need to consider maternal depression in the context of the child’s global rearing environment and in relation to the attainment of specific developmental goals.”

The study is published in the August 2009 issue of the Journal of the American Academy of Child
Adolescent Psychiatry

Source: Journal of the American Academy of Child and Adolescent Psychiatry