New research show that risks of developing bipolar affective disorder is increased if a woman experiences a psychiatric episode within the first 30 days after childbirth.

"Childbirth has an important influence on the onset and course of bipolar affective disorder, and studies have shown that episodes of post-partum psychosis are often best considered as presentations of bipolar affective disorder occurring at a time of dramatic psychological and physiological change," the researchers said in the report which was published in Archives of General Psychiatry.

The researchers led by Trine Munk-Olsen, Ph.D., of the National Centre for Register-Based Research, Arhus University in Denmark, collected data on 120,378 women from 1950 to 1991who had a history of a first-time psychiatric contact with any type of psychiatric disorder excluding bipolar affective disorder.

A total of 2,870 of these women had their initial psychiatric contact within the first year after delivery of their first child. During follow-up, 3,062 of the 120,378 women were diagnosed of bipolar affective disorder, of which 132 had their initial psychiatric contact 0 to 12 months post-partum.

Researchers found a significantly higher conversion rate to bipolar affective disorder in women having their initial contact within the first post-partum month. In addition, evidence that the severity of the initial post-partum psychiatric episode may be important, as inpatient admissions were associated with a higher conversion rate than were outpatient contacts, were found.
After fifteen years from initial psychiatric contact, 13.87 percent of women with onset in the immediate post-partum period (0 to 30 days) had converted to bipolar disorder, the study said.

"The present study confirms the well-established link between childbirth and bipolar affective disorder and specifically adds to this field of research by demonstrating that initial psychiatric contact within the first 30 days post-partum significantly predicted conversion to bipolar affective disorder during the follow-up period," the authors conclude.