I recently did some research for a women’s magazine about depression in young women (ages 18 to 30). The editors wanted to know why so many more women than men struggle with depression.

I got out my copy of “A Deeper Shade of Blue: A Woman’s Guide to Recognizing and Treating Depression in Her Childbearing Years” by Ruta Nonacs, M.D., Ph.D., whose work fascinates me. Here are some excerpts from her book that help to explain why women are more vulnerable to depression and anxiety:

Depression is about twice as common in women as in men, with about 1 woman in 4 suffering from depression at some point during her lifetime. Depression may strike at any time, but women appear to be particularly vulnerable during their childbearing years. Women are at highest risk for depression during pregnancy and shortly after delivery. One recent study indicated that as many as 25 percent of women suffer from depression during either pregnancy or postpartum period. Yet, in most of these women, the illness goes unrecognized and untreated.

Many have attributed this disparity to the various stresses women face as a result of their gender and the demands women face as they occupy multiple–and often conflicting–roles within the family, in the community, and at work. Over the last decade, researchers have also focused on the role of reproductive hormones, particularly estrogen.

In is interesting to note that before adolescence, rates of depression are about the same among girls and boys. Thing begin to shift between the ages of eleven and thirteen. Over these years, there is a dramatic rise in the prevalence of depression in girls, and by the age of fifteen females are twice as likely as males to suffer from depression. What happens to create this gender gap during adolescence is a topic of intense debate and research. There is no doubt that adolescence is a time characterized by dramatic psychological and physical changes for women, and it is easy to imagine that this tumultuous transition may render adolescent girls more vulnerable to depression. However, a woman’s risk for depression persists beyond puberty and she remains at higher risk for depressive illness than a man throughout her entire adult life.

At no other point are women more vulnerable to depression than during their childbearing years. How can we explain this susceptibility to depression? From a psychological standpoint, this is a time when she is faced with many life-changing and potentially stressful transforming events; during this span of years a woman pursues her education, career, marriage, childbearing, and child rearing. These changes provide the emotional context within which depression may take hold. However, in addition to being an emotionally charged time, the childbearing years are also characterized by dramatic hormonal shifts related to reproductive functioning. Every month a woman completes a menstrual cycle and is exposed to rising and then falling levels of reproduce hormones. During pregnancy and after delivery, a woman experiences even more dramatic shifts in this reproductive hormonal environment. Many specialists in the field of women’s mental health have postulated that it is the combination of psychological stressors and hormonal events that make women so vulnerable to depression during the childbearing years.

Not only is a woman exposed to different types of hormones and different levels of these hormones than a man, throughout her reproductive years she experiences constant hormonal fluctuations. … Experts believe that these hormonal shifts may act as a trigger for depression in some women and that women who have premenstrual mood changes may also be more vulnerable to depression at other times when exposed to significant hormonal fluctuations, such as after childbirth or during the transition to menopause.

While it is clear that certain women may be more vulnerable to these hormonal shifts, it is not clear whether hormonal factors increase vulnerability in all women. Some researchers hypothesize that these monthly hormonal changes act as a type of recurrent stressor, and with these repetitive insults, the underlying architecture of a woman’s brain is somehow altered so that is more susceptible to depression.

To read more Beyond Blue, go to www.beliefnet.com/beyondblue, and to get to Group Beyond Blue, a support group at Beliefnet Community, click here.