This study examines the association between perinatal depression (PND) and the risk of suicidal behavior, including suicide attempts and completed suicides, in a nationwide cohort of Swedish women. The study found that women with PND had a significantly higher risk of suicidal behavior compared to women without PND. The risk was particularly high in the first year after diagnosis and remained elevated over a 18-year follow-up period. Women with PND were more likely to have suicidal behavior than their PND-free siblings, indicating that PND is associated with an increased risk of suicidal behavior beyond the risk associated with psychiatric disorders occurring before the perinatal period. The study also found that the risk of suicidal behavior was higher among women with postnatal depression than those with antenatal depression. The most common method of suicidal behavior among women with PND was poisoning, while hanging was associated with the highest hazard ratio. The study highlights the need for vigilant clinical monitoring and interventions for women with PND to prevent suicidal behavior. The findings suggest that PND is a significant risk factor for suicidal behavior, and that long-term monitoring is necessary to address this risk. The study was conducted using nationwide register data and included a large sample size, allowing for detailed subgroup analyses. The study's strengths include the use of nationwide data and advanced analytic methods, while limitations include potential underestimation of suicidal behavior and the inability to capture all cases of PND. The study's results have important implications for clinical practice, emphasizing the need for mental health support and monitoring for women with PND.This study examines the association between perinatal depression (PND) and the risk of suicidal behavior, including suicide attempts and completed suicides, in a nationwide cohort of Swedish women. The study found that women with PND had a significantly higher risk of suicidal behavior compared to women without PND. The risk was particularly high in the first year after diagnosis and remained elevated over a 18-year follow-up period. Women with PND were more likely to have suicidal behavior than their PND-free siblings, indicating that PND is associated with an increased risk of suicidal behavior beyond the risk associated with psychiatric disorders occurring before the perinatal period. The study also found that the risk of suicidal behavior was higher among women with postnatal depression than those with antenatal depression. The most common method of suicidal behavior among women with PND was poisoning, while hanging was associated with the highest hazard ratio. The study highlights the need for vigilant clinical monitoring and interventions for women with PND to prevent suicidal behavior. The findings suggest that PND is a significant risk factor for suicidal behavior, and that long-term monitoring is necessary to address this risk. The study was conducted using nationwide register data and included a large sample size, allowing for detailed subgroup analyses. The study's strengths include the use of nationwide data and advanced analytic methods, while limitations include potential underestimation of suicidal behavior and the inability to capture all cases of PND. The study's results have important implications for clinical practice, emphasizing the need for mental health support and monitoring for women with PND.