PreParent: Internet-based Digital Tools to Screen for and Prevent Postpartum Depression in Parents-to-be

The goal of this randomized controlled study is to evaluate whether an online intervention that combines psychoeducation and affective cognitive training can help prevent postpartum depression in pregnant women and co-parents who have been identified as having risk factors for postpartum depression through an online screening tool. A total of 520 expecting parents will be enrolled in the intervention trial. Researchers will compare the online intervention to care as usual (CAU) in the Danish healthcare system to determine whether the intervention has a better preventive effect. The study also involves a low-risk comparison group (n = 5250) who will not receive the intervention but will complete the same assessments for background comparisons. The main question is: \- Does the online intervention reduce the number of mothers who develop postpartum depression during the first six months after birth? Other questions the study addresses include: * How severe mothers' depressive symptoms are during the first six weeks postpartum, based on weekly online ratings? * How do parents report their own stress levels and their infant's development six months after birth? The study will also explore: * How many co-parents develop postpartum depression during the first six months postpartum. * Whether mothers experience additional benefit if their co-parent also completes the intervention. Participants will: * Complete a 4-5-week online intervention with 8-9 modules that include psychoeducation and cognitive-affective training. * Complete online questionnaires and outcome assessments from home. * Participate in a diagnostic interview by phone after birth.