Psychiatric disorders with postpartum onset: Possible early manifestations of bipolar affective disorders

Context: Childbirth has an important influence on the onset and course of bipolar affective disorder, and it is well established that there may be a delay of many years before receiving a diagnosis of bipolar disorder following an initial episode of psychiatric illness. Objective: To study to what extent psychiatric disorders with postpartum onset are early manifestations of an underlying bipolar affective disorder. Design: Survival analyses were performed in a register-based cohort study linking information from the Danish Civil Registration System and the Danish Psychiatric Central Register. Setting: Denmark. Participants: A total of 120 378 women with a first-time psychiatric inpatient or outpatient contact with any type of mental disorder excluding bipolar affective disorder. Main Outcome Measures: Each woman was followed up individually from the day of discharge, with the outcome of interest being an inpatient or outpatient contact during the follow-up period with a first-time diagnosis of bipolar affective disorder. Results: A total of 3062 women were readmitted or had an outpatient contact with bipolar affective disorder diagnoses. A postpartum onset of symptoms within 0 to 14 days after delivery predicted subsequent conversion to bipolar disorder (relative risk = 4.26; 95% CI =3.11-5.85). Approximately 14% of women with first-time psychiatric contacts during the first postpartum month converted to a bipolar diagnosis within the 15-year follow-up period compared with 4% of women with a first psychiatric contact not related to childbirth. Postpartum inpatient admissions were also associated with higher conversion rates to bipolar disorder than outpatient contacts (relative risk = 2.16; 95% CI = 1.27-3.66). Conclusions: A psychiatric episode in the immediate postpartum period significantly predicted conversion to bipolar affective disorder during the follow-up period. Results indicate that the presentation of mental illness in the early postpartum period is a marker of possible underlying bipolarity