Background: Postpartum period is associated with an increased risk of bipolar disorder diagnosis and relapse, mainly major depressive episode. Onset during this period might be associated with specific characteristics. Aim: To compare the socio-demographic and clinical characteristics of parous women presenting with bipolar disorder and an index depressive episode occurring during or outside the postpartum period. Methods: Using the multicenter cohort FACE-BD (FondaMental Academic Centers of Expertise for Bipolar Disorders), we considered all women who started their BD with a major depressive episode and have at least one child. We compared two groups depending on the onset: in or outside the postpartum period. Results: Among the 759 women who started BD with a major depressive episode, 93 (12.2%) had a postpartum onset, and 666 (87.8%) had not. Women who started BD in the postpartum period with a major depressive episode have a more stable family life, more children, an older age at onset, more Bipolar 2 disorder, less history of suicide attempts, less depressive episodes and more mood stabilizer treatments as compared to those who started with a major depressive episode outside the postpartum period. The multivariable logistic regression showed that women with an onset in the postpartum period had significantly more children, less lifetime depressive episodes and a lower rate of history of suicide attempts as compared to women with an onset outside the postpartum period. Discussion: Our results suggest that women starting their BD with postpartum depression have a more favorable course of BD, especially less history of suicide attempt and less lifetime depressive episodes.