Background: Retrospective studies have consistently indicated an association between maladaptive parenting and borderline personality disorder (BPD). This requires corroboration with prospective, longitudinal designs. We investigated the association between suboptimal parenting and parent conflict in childhood and BPD symptoms in late childhood using a prospective sample.

Method: A community sample of 6050 mothers and their children (born between April 1991 and December 1992) were assessed. Mothers' family adversity was assessed during pregnancy and parenting behaviours such as hitting, shouting, hostility and parent conflict across childhood. Intelligence quotient (IQ) and DSM-IV Axis I diagnoses were assessed at 7-8 years. Trained psychologists interviewed children at 11 years (mean age 11.74 years) to ascertain BPD symptoms.

Results: After adjustment for confounders, family adversity in pregnancy predicted BPD probable 1 to 2 adversities: odds ratio (OR)=1.34 [95% confidence interval (CI) 1.01-1.77]; >2 adversities: OR 1.99 (95% CI 1.34-2.94) and definite 1 to 2 adversities: OR 2.48 (95% CI 1.01-6.08) symptoms. Each point increase in the suboptimal parenting index predicted BPD probable: OR 1.13 (95% CI 1.05-1.23) and definite: OR 1.28 (95% CI 1.03-1.60) symptoms. Parent conflict predicted BPD probable: OR 1.19 (95% CI 1.06-1.34) and definite: OR 1.42 (95% CI 1.06-1.91) symptoms. Within the path analysis, the association between suboptimal parenting and BPD outcome was partially mediated by DSM-IV diagnoses and IQ at 7-8 years.

Conclusions: Children from adverse family backgrounds, who experience suboptimal parenting and more conflict between parents, have poor cognitive abilities and a DSM-IV diagnosis, are at increased risk of BPD symptoms at 11 years.