The condition's neurobiology has not been defined, but modern researchers widely presume that hormonal shifts initiate, if not sustain, the disease process. In the 1960s, researchers treated women with long-acting estrogen immediately after delivery and were able to suppress most symptoms of "maternity" blues. Abnormalities in thyroid and pituitary function have also been implicated. Today, SSRI (selective serotonin reuptake inhibitor) antidepressants such as Prozac and Paxil are the most common treatment.
Not surprisingly, psychological factors help determine vulnerability. Mothers who didn't want to get pregnant experience greater risk for milder forms of postpartum illness than those who wanted their babies. The birth of a premature infant or difficult labor also enhances risk, as does a mother's feeling that she is not getting adequate emotional and material support. Mothers report the baby blues more often in the United States than in other countries, but the condition cuts across cultures.
Edward H. Hagen, an anthropologist at the University of California at Santa Barbara, offers a sociobiological theory of postpartum depression. He argues that diminished maternal investment in the offspring could be adaptive under conditions of insufficient intimacy and resources. Writes Hagen, "Because human infants require enormous amounts of investment, ancestral mothers needed to carefully assess both the availability of support from the father and family members and infant viability before committing to several years of nursing and childcare."
What distinguishes the baby blues from something more malignant? Families should be on the lookout for distress that doesn't disappear after a week or so, as well as symptoms that interfere with caretaking, such as sluggishness, sadness, uncontrollable crying, hopelessness, a sense of doom, poor concentration, confusion, and memory loss. Other markers include obsessive checking on the infant or an irrational fear on the mother's part that she might harm the baby or herself.
We should, however, resist the modern tendency to label all emotional discomfort—shyness in adults, for example—as sicknesses requiring medication. Postpartum doldrums are natural, whether their underlying causes be hormonal or psychological. For most mothers most of the time, the best remedies are helpful mates, supportive families and friends, and time.
Sally Satel, a psychiatrist and resident scholar at the American Enterprise Institute, is editor of When Altruism Isn't Enough: The Case for Compensating Kidney Donors.
Photograph of Andrea Yates by Ho/Reuters.