Researchers have long connected mood disorders and pregnancy. But a study coming out of Western is boiling down some of the specifics, suggesting women who suffered from depression prior to pregnancy should be monitored for manic symptoms, characteristic of bipolar disorder, in the postpartum period.
While women's reproductive events (such as pregnancy, the postpartum period and menopause) are commonly associated with mood disorders, childbirth is a more dramatic event, explained Dr. Varinder Sharma, a psychiatrist who teaches in the Schulich School of Medicine & Dentistry in the departments of Psychiatry and Obstetrics and Gynecology.
Sharma recently co-authored a paper, "A prospective Study of Diagnostic Conversion of Major Depressive Disorder to Bipolar Disorder in Pregnancy and Postpartum," in the journal Bipolar Disorders, outlining the importance of monitoring postpartum women who suffer from depression and watching for symptoms of hypomania.
"We know childbirth is a potent and specific trigger for mania and hypomania. What I wanted to do was to see, if you have a group of women with just depression, how many of them would convert to bipolar disorder after giving birth," Sharma said. "A large number of women do convert."
His team found the incidence of diagnostic conversion – from depression to bipolar disorder – in postpartum women was 11-18 times higher than reported in nonpostpartum women.
"If you look at the literature on postpartum mental illness, there's lots of emphasis on postpartum depression; not much attention is paid to bipolar disorder," Sharma said.
He noted bipolar disorder in postpartum women tends to go unnoticed following childbirth.
"When physicians and other care givers are assessing women with postpartum depression, they have to screen them for bipolar disorder. This has important treatment implications and there are some safety issues as well. Bipolar disorder is more likely associated with suicide, and, perhaps, infanticide."
That's why it is important to know the diagnosis as early as possible, he noted. That will ensure prompt and proper treatment, before symptoms escalate. Prescribing antidepressants to a woman whose diagnosis has converted to bipolar disorder won't be effective and could exacerbate symptoms of mania, Sharma explained.
"If you look at women who get hospitalized for psychiatric reasons within the first couple of weeks after childbirth, a large number of them have bipolar disorder," he said.
"We know childbirth is perhaps the most important and most potent trigger of bipolar disorder. We need to understand why that is the case, what is so unique about childbirth that it's associated with such high risk," he continued.
It's possible genetic factors, a family history of bipolar disorder, hormonal changes and sleep loss following pregnancy, contribute to the high risk. Sharma and his team will continue to examine these factors, in hopes of better understanding the underlying cause of the increased diagnostic conversion of depression to bipolar disorder in postpartum women.
"For us to understand bipolar disorder in women, we have really neglected the role of hormonal changes," he said.
"We now want to look at women who have just postpartum depression, to see whether the presence of manic symptoms (changes) in response to treatment."
Explore further: Preventive treatment of pregnant women at high postpartum psychosis risk