Background: Given the estimated high rate of unintended pregnancies, it is important to investigate long-term effects on psychological distress in women carrying an unintended pregnancy to term. However, research into associations between unintended pregnancies carried to term and psychological distress postpartum is mixed, and especially, evidence on long-term associations is scarce. Objective: To examine whether carrying an unintended pregnancy to term is associated with maternal psychological distress later in life, up to 12 years postpartum. Design: This study is based on the population-based birth cohort study ‘Amsterdam Born Children and their Development’ study, which included pregnant people in 2003 ( n = 7784) and followed them up until 12 years postpartum. Methods: Unintended pregnancy was measured as a multidimensional construct, based on self-reported data around 16 weeks gestation on pregnancy mistiming, unwantedness and unhappiness. Symptoms of maternal psychological distress were assessed around 3 months, 5 years and 12 years postpartum using multiple questionnaires measuring symptoms of depression, anxiety and stress. Multiple structural equation modelling models were analysed, examining the associations between dimensions of unintended pregnancy and maternal psychological distress per time point, while controlling for important co-occurring risks. Results: Pregnancy mistiming and unhappiness were significant predictors of more maternal psychological distress around 3 months postpartum. Around 5 years postpartum, only pregnancy mistiming was positively associated with maternal psychological distress. Dimensions of unintended pregnancy were no longer associated with maternal psychological distress around 12 years postpartum. Strikingly, antenatal psychological distress was a much stronger predictor of maternal psychological distress than pregnancy intention dimensions. Conclusion: Those who carried a more unintended pregnancy to term reported more symptoms of psychological distress at 3 months and ...