The majority of research on conduct disorder suggests that there are a significantly greater number of males than females with the diagnosis, with some reports demonstrating a threefold to fourfold difference in prevalence.[44] However, this difference may be somewhat biased by the diagnostic criteria which focus on more overt behaviors, such as aggression and fighting, which are more often exhibited by males. Females are more likely to be characterized by covert behaviors, such as stealing or running away. Moreover, conduct disorder in females is linked to several negative outcomes, such as antisocial personality disorder and early pregnancy,[45] suggesting that sex differences in disruptive behaviors need to be more fully understood.