Women’s mental health during pregnancy has important implications not only for the well-being of the mother, but also for the development, health, and well-being of her unborn child. A growing body of empirical evidence from population-based studies suggests that psychosocial stress during pregnancy may exert a significant influence on pregnancy outcomes, fetal development, and infant birth outcomes, such as birth weight and length of gestation, even after controlling for the effects of established socio-demographic, obstetric, and behavioral risk factors (Andersson, Sundstrom-Poromaa, Wulff, Astrom, & Bixo, 2006; Stewart, 2007; Talge, Neal, & Glover, 2007). Among the most common mental illnesses occurring in pregnancy related to elevated levels of psychosocial stress are depression and anxiety.