Pregnant women with mental disorders are more likely to be obese than pregnant women without mental disorders. This chapter reviews the evidence on how obesity in pregnancy is related to mental disorders and the implications of this for the management of obesity in pregnancy. Common mental disorders include depressive disorders and anxiety disorders. Binge eating disorder was included in the American Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) as a provisional eating disorder. Clinical studies have found that women being treated for bipolar disorder are at increased risk of eating disorders. Structured cognitive behavioral therapy programs are well-established treatments for binge eating disorder, but while these typically reduce bingeing behavior, they appear less effective at reducing weight. Moderate physical activity and nutritional advice are recommended for pregnant obese women and could therefore indirectly improve mental health as well as physical health.