And those with a history of depression any time before their pregnancy -- about one in every four women -- are about twice as likely as other women to show signs of depression while pregnant, the study results show.
The study of 3,472 pregnant women, conducted by researchers from the U-M Depression Center in the waiting rooms of 10 Michigan obstetrics clinics, is being published May 22 in the Journal of Women's Health.
The results reveal troubling under-diagnosis and under-treatment of depression in pregnancy. Twenty percent of the women scored high on a standard survey of depression symptoms, but of those, only 13.8 percent were receiving any mental health counseling, drugs or other treatment. Only about 24 percent of those who had had depression in the last six months were receiving treatment during pregnancy.
Growing scientific evidence suggests that hormone imbalances associated with depression can affect the fetus or put a woman at higher risk of post-partum depression. Population-based evidence has also shown that babies of depressed mothers do worse at birth, and beyond, than other infants.
"A woman's childbearing years are also her highest-risk time for depression. Doctors used to think of pregnancy as a 'honeymoon' away from depression risk, but this is turning out to be a myth," says lead author Sheila Marcus, M.D., a clinical assistant professor of psychiatry at the U-M Medical School. "We now know that the hormones and brain chemistry involved in depression are known to be affected by changes in other hormones related to pregnancy. And we know this may affect the fetus."
Fortunately, Marcus notes, recent studies have shown that some standard depression treatments -- including some antidepressant drugs -- do not appear to increase the risk of birth defects. A few longer-term studies suggest that infants exposed to some antidepressants in pregnancy look very similar to their siblings who are not exposed, both in terms of IQ and learning problems, when compared at age 5. But she notes that more work is necessary in this area.
She and her colleagues hope their study will help raise awareness among pregnant women, and their doctors and midwives, about the need to recognize depression symptoms and seek treatment.
Explains Marcus, "We need to educate women about the signs of depression, and encourage them to be open about how they're feeling during pregnancy and after delivery, rather than feeling guilty and embarrassed."
The U-M Depression Center, the nation's only comprehensive center for depression treatment, research and education, has launched a Web site about depression designed specifically for women, www.med.umich.edu/womensguide. The site recognizes that one in four women will experience depression sometime in her life, and that hormone-related life transitions such as puberty, pregnancy and menopause are strongly associated with an increased risk.
The team led by Marcus, who is also the clinical director of the psychiatry division of the U-M Depression Center, conducted the survey over a three-year period at a range of clinics where pregnant women were awaiting their prenatal doctor's visits. Ninety percent of the women who were approached agreed to complete the survey. Marcus notes that the high participation and completion rate show that screening for depression in the doctor's office waiting room may be feasible across the board. Such screening is becoming standard at U-M obstetrics clinics.
The survey included a standardized validated questionnaire of current distress and depressive feelings (CES-D), a standardized validated questionnaire about alcohol use (TWEAK), and questions about lifetime and recent depression history and treatment, overall health, use of prescription drugs and demographic information.
The women ranged in age from 18 to 46 years, with an average age of 28.6 years, and were from diverse racial and ethnic backgrounds with about 73 percent white. They were, on average, about 25 weeks into their pregnancies, but gestation ages ranged from 3 to 41 weeks.
The researchers used a cutoff score of 16 or above on the CES-D scale to indicate current minor depression. They also asked the women whether they had had a period of two or more weeks in the last six months, or in their lifetime, when they had consistently felt sad, blue or depressed, or lost all interest in things such as work -- an indication of major depression.
Twenty-eight percent of the women reported a lifetime history of major depression, and 42 percent of them scored above 16 on the CES-D, indicating current minor or major depression.
This recurrence of depression during pregnancy, Marcus feels, is a significant issue that deserves special attention. Because of depression's cyclical nature, women who have had depression at any time in their lives may be symptom-free when they become pregnant. But the new data suggest that they can start experiencing a return of their symptoms during pregnancy -- and their increased risk of post-partum depression is already well known.
Women who reported being unemployed or without a partner, using alcohol and tobacco during pregnancy, or having lower levels of education were all more likely to score above 16 on the CES-D scale of distress and depression.
The study also showed that the vast majority of currently or previously depressed women -- 86 percent of those with current symptoms, 88 percent of those with lifetime history of depression and 76 percent of those with depression in the last six months -- had not seen a counselor or received other treatment in recent months. In fact, about half of the women in the study who had been taking medications for depression before they got pregnant stopped once they conceived.
This under-treatment, and treatment stoppage, stem from a misconception that antidepressants are unsafe for pregnant women and fetuses, says Marcus.
Some drugs -- such as lithium used to treat the bipolar form of depression -- are indeed associated with an increased risk of birth defects.
But no increased risk is seen with other drugs. For instance, a paper published in the March 2003 issue of the American Journal of Obstetrics and Gynecology showed that the rate of birth defects and birth complications among the babies of women who took antidepressants called SSRIs was the same as for non-depressed women.
"There are two kinds of treatment that can be thought about for pregnant women: interpersonal psychotherapy, and the SSRI and tricyclic classes of medications," says Marcus. SSRIs include popular drugs such as Prozac, Paxil, Zoloft and Celexa. And while it wouldn't be feasible to do a major randomized, controlled, prospective study of drugs in pregnant women with depression, population studies and the need to balance risk with benefit should help ease concerns.
Medications and psychotherapy can regulate the stress hormones and other brain chemistry involved in depression, helping alleviate women's symptoms, improve their quality of life, and reduce their chances of debilitating post-partum depression, self-harming acts and suicide.
But this moderating effect may also spare the fetus lasting effects, Marcus suspects. Studies have shown that babies born to depressed mothers have lower birth weights, higher risk of premature birth and birth complications, delayed cognitive and language development, and more behavioral problems. Scientists are beginning to speculate that these effects may be due in part to the unbalanced sea of hormones and reduced blood flow that these fetuses are exposed to in the womb. Even minor depression, Marcus notes, may affect the fetus.
To explore this issue further, the U-M Depression Center team has embarked on a major study involving pregnant women before and after they deliver, and from their newborn babies. Saliva from cheek swabs, and blood samples from the mother and the newborn's umbilical cord, will be examined for levels of cortisol, a hormone that's associated with stress and depression. The researchers, led by Delia M. Vazquez, M.D., an associate professor of pediatrics and psychiatry at the U-M, will follow the mothers and babies for more than a year after birth.
In the meantime, Marcus notes, the findings in the newly published paper should help clinicians and women alike understand the importance of recognizing and treating depression in pregnancy. "Women with a history of depression should be targeted for more intensive assessment during early pregnancy," Marcus says. "And it may be useful for clinicians to watch for depression in those who are not working, are unmarried, have greater health complaints, and those who use alcohol and cigarettes during pregnancy."
In addition to Marcus, the study's authors include Heather Flynn, Ph.D., a psychologist and member of the U-M Depression Center Women's Mood Disorders Program; and Frederic C. Blow, Ph.D., and Kristen L. Barry, Ph.D., of the U-M Department of Psychiatry and the VA Ann Arbor Healthcare Center. The research was funded by the University of Michigan Health System.
Reference: Journal of Women's Health, Vol. 12, No. 4, May, 2003