Women who are generally quiet, shy and anxious may be more likely than others to become depressed after giving birth, new research suggests.

In a study of 277 pregnant women, researchers in the Netherlands found that those who were highly introverted and highly neurotic were at increased risk of developing postpartum depression in the year after giving birth.

These women were nearly seven times more likely than their more outgoing and laid-back peers to be depressed when their babies were 12 months old.

Researchers led by Dr. Gerda J.M. Verkerk of Tilburg University used standard questionnaires to gauge introversion and neuroticism among women late in pregnancy. The women were also screened for Depression at this time and again 3, 6 and 12 months after giving birth.

People who are highly introverted prefer to keep to themselves and tend to avoid social situations; they also generally keep their feelings to themselves. Highly neurotic individuals are generally anxious and sensitive, and tend to be “moody” or easily stressed out.

The combination of the two personality traits, Verkerk’s team found, appeared to increase a woman’s risk of developing postpartum depression -even when the researchers took into account risk factors for the condition, including a history of general depression.

Among women with no history of Depression, 15 percent of those who were highly introverted and highly neurotic had postpartum depression three months after giving birth, compared with 2.5 percent of women who scored low on measures of the two traits. By the one-year mark, the disparity in depression rates had increased to 25 percent versus 1.3 percent, respectively.

In fact, the personality combination was the only independent predictor of a mother’s depression risk throughout the first year of her infant’s life, according to findings published in the journal Psychosomatic Medicine. A history of depression was a risk factor only during the early postpartum period.

The findings, Verkerk and her colleagues conclude, suggest that standard personality measures could help identify women at particular risk of postpartum depression.

postpartum depression is thought to affect about 10 percent of new mothers. Unlike the “baby blues” that commonly arise soon after delivery, postpartum depression is a more serious and lasting condition that may begin in the days following delivery or develop gradually during the infant’s first year.

The cause isn’t fully clear, but experts believe that hormonal changes after delivery, along with the social and psychological changes that a baby brings to a woman’s life, all play a role.

The current findings, according to Verkerk’s team, point to certain personality factors that may make a woman more vulnerable.

“It is now time,” they write, “that personality be included in the early identification of those women who are at increased risk for depression in the postpartum period.”

SOURCE: Psychosomatic Medicine, July/August 2005.