By Rick Nauert PhD Senior News EditorReviewed by John M. Grohol, Psy.D. on December 10, 2010

Fetal development is influenced by a wealth of factors, including maternal depression. University of Michigan researchers have found that more severe depression in mothers during pregnancy was linked to higher levels of stress hormones in their children at birth and other neurological and behavioral differences.

“The two possibilities are that they are either more sensitive to stress and respond more vigorously to it, or that they are less able to shut down their stress response,” says the study’s lead investigator, Delia M. Vazquez, M.D.

The analysis, which appears online ahead of print publication in Infant Behavior and Development, examined links between maternal depression and the development of an infants’ neuroendocrine system, which controls the body’s stress response and impacts moods and emotions.

At two weeks old, researchers found that the children of depressed mothers had decreased muscle tone compared to those born to mothers who weren’t depressed, yet they adjusted more quickly to stimuli like a bell, rattle or light – a sign of neurological maturity.

“It’s difficult to say to what extent these differences are good or bad, or what impact they might have over a longer time frame,” says the study’s lead author, Sheila Marcus, M.D., clinical director of U-M’s Child and Adolescent Psychiatry Section.

“We’re just beginning to look at these differences as part of a whole collection of data points that could be risk markers. These in turn would identify women who need attention during pregnancy or mother/infant pairs who might benefit from postpartum programs known to support healthy infant development through mom/baby relationships.”

The longer-term question for researchers is the degree to which the hormonal environment in the uterus may act as a catalyst for processes that alter infant gene expression, neuroendocrine development and brain circuitry – potentially setting the stage for increased risk for later behavioral and psychological disorders.

While cautioning against alarm, the researchers recommended that mothers experiencing symptoms of depression during pregnancy talk to a therapist.

They also noted that interventions aimed at mother-child bonding after birth can act as countermeasures, stimulating children’s neurological development and lowering the possible effects of stress hormone production early in life.

Postpartum depression is one of the most common complications of pregnancy and up to 1 in 5 women may experience symptoms of depression during pregnancy.

Along with tracking the mothers’ depressive symptoms throughout gestation, U-M researchers took samples of umbilical cord blood right after birth. They found elevated levels of adrenocorticotropic hormone (ACTH) in babies born to mothers with depression. ACTH tells the adrenal gland to produce the stress hormone cortisol.

Cortisol levels, however, were similar in children of mothers with varying levels of depression, likely an indication of the high level of stress associated with the birth itself, the researchers note.

Source: University of Michigan