Conduct disorder (CD) is a serious disruptive behaviour disorder that is diagnosed in children who display repetitive and persistent antisocial behaviour, such as violence, robbery and vandalism. Children with CD present substantial costs to society, and are the group of children most commonly referred to mental health services. Further, CD is a strong predictor of adult Antisocial Personality Disorder and psychopathy. Research to date on the biological associates of CD has mostly compared the anatomy and function of specific brain regions in people with CD to controls. However, there is increasing recognition that brain regions do not act in isolation. Rather, they form part of integrated neural systems. Nevertheless, to date, there have been no studies on anatomical ‘connectivity’ in CD. Also there are few studies of how prenatal environment modulates the development of human limbic ‘social brain’ regions that are implicated in CD, and other abnormalities in social development. For example, prior studies reported behaviour problems in babies and children of mothers with elevated levels of stress or anxiety during pregnancy. Preliminary evidence suggests that these maternal emotional factors modulate intrauterine environment (e.g. through the stress hormone cortisol); and so may alter the development of limbic brain structures (such as the amygdala and orbitofrontal cortex) that are crucial to emotion processing and social cognition. However, to date, only one human study has examined the association between prenatal maternal mood and altered development of neural systems in children.