Background. The aetiological pathways to borderline personality disorder (BPD) remain only partly elucidated. Retrospective research indicates that prenatal adversity may be an important early risk factor in the development of BPD. This requires corroboration with prospective longitudinal studies. Method. A community sample of 6050 mothers and their children (born between April 1991 and December 1992) were assessed. Maternal anxiety and depression and maternal alcohol and tobacco consumption were assessed during pregnancy (18 and 32 weeks gestation). Postnatal risks, including maladaptive parenting (suboptimal parenting and parent conflict), family adversity, maternal anxiety and depression and maternal alcohol and tobacco consumption, were assessed during early childhood. Internalizing and externalizing symptoms were assessed in late childhood. Trained psychologists interviewed children in late childhood to ascertain the presence of BPD (at least five probable/definite symptoms). Results. In unadjusted analyses, all prenatal risk factors (i.e. maternal alcohol and tobacco consumption and maternal anxiety and depression) were significantly associated with BPD. Following adjustment for sex, birthweight and postnatal exposure to anxiety and depression respectively, maladaptive parenting, family adversity and child’s internalizing and externalizing symptoms, prenatal anxiety at 18 weeks gestation [odds ratio (OR) 1.57, 95% confidence interval (CI) 1.18-2.09] and depression at 18 weeks (OR 1.59, 95% CI 1.08-2.32) and 32 weeks (OR 1.57, 95% CI 1.14-2.18) gestation remained significantly associated with BPD. Conclusions. This study provides prospective evidence of associations between prenatal adversities and BPD at 11-12 years. Prenatal anxiety and depression were independently associated with BPD, suggesting that they may exert direct effects on BPD during the prenatal period. This highlights the importance of programmes to reduce maternal stress during pregnancy.