"These findings show we need to pay more attention to depression before pregnancy," said Evelyn Whitlock, MD, MPH, senior investigator at the Kaiser Permanente Center for Health Research and co-author of the study. "Doctors and the public tend to focus more on postpartum depression because of the huge gap between a new mother's joyful expectations and the crushing reality of depression."

The consequences of postpartum depression, which affects 400,000 women in the United States, can be devastating. It can inhibit a woman's ability to bond with her infant, relate to the child's father, and perform daily activities.

"While postpartum depression clearly is an important concern," Whitlock added, "we also need to consider the mental health and treatment needs of the many women who are depressed right before or during their pregnancies."

Investigators at the Kaiser Permanente Center for Health Research profiled 4,398 women who gave birth between 1998 and 2001. They found that 8.7 percent were identified as depressed in the nine months before pregnancy, 6.9 percent during pregnancy, and 10.4 percent in the nine months following childbirth. A total of 15.4 percent – more than one in seven women – were depressed during at least one of these three periods. Nearly three-fourths of women with postpartum depression also were depressed before pregnancy, and more than half of the women depressed before pregnancy then became depressed during their pregnancy, the study found.

"The biggest news here is that we need to manage depression as a chronic condition in women of childbearing age, rather than assume depression is a temporary condition that can be either triggered or relieved by getting pregnant or giving birth," Whitlock said. "Women with a history of depression should be closely monitored for depressive symptoms during prenatal and postpartum care. And, given recent evidence showing that relapse of depression is twice as common in pregnant women with major depression who stop taking antidepressants after becoming pregnant as women who continue treatment, a choice of effective and safe treatment options for depressed pregnant women is very important."

The study also found that 93.4 percent of the women identified with depression before, during, or after pregnancy had a mental health visit or received antidepressants. Nearly three-fourths of depressed women received an antidepressant – 77 percent before pregnancy, 67 percent during pregnancy and 82 percent after delivery. Selective serotonin reuptake inhibitor antidepressants were the most common type of antidepressants prescribed, and 180 women (4 percent of all pregnant women) received them during pregnancy. The authors note that women received these medications before concerns were publicized about possible effects of SSRIs on persistent pulmonary hypertension in newborns and on cardiovascular malformations.

The study was funded by a contract from the Centers for Disease Control and Prevention. The contract as administered by America's Health Insurance Plans. The study's authors are affiliated with the Centers for Disease Control and Prevention or with Kaiser Permanente's Center for Health Research.